Polycarpus takes part in the "Field of Wonders" TV show. The participants of the show have to guess a hidden word as fast as possible. Initially all the letters of the word are hidden.

The game consists of several turns. At each turn the participant tells a letter and the TV show host responds if there is such letter in the word or not. If there is such letter then the host reveals all such letters. For example, if the hidden word is "abacaba" and the player tells the letter "a", the host will reveal letters at all positions, occupied by "a": 1, 3, 5 and 7 (positions are numbered from left to right starting from 1).

Polycarpus knows m words of exactly the same length as the hidden word. The hidden word is also known to him and appears as one of these m words.

At current moment a number of turns have already been made and some letters (possibly zero) of the hidden word are already revealed. Previously Polycarp has told exactly the letters which are currently revealed.

It is Polycarpus' turn. He wants to tell a letter in such a way, that the TV show host will assuredly reveal at least one more letter. Polycarpus cannot tell the letters, which are already revealed.

Your task is to help Polycarpus and find out the number of letters he can tell so that the show host will assuredly reveal at least one of the remaining letters.

Input

The first line contains one integer n (1 ≤ n ≤ 50) — the length of the hidden word.

The following line describes already revealed letters. It contains the string of length n, which consists of lowercase Latin letters and symbols "*". If there is a letter at some position, then this letter was already revealed. If the position contains symbol "*", then the letter at this position has not been revealed yet. It is guaranteed, that at least one letter is still closed.

The third line contains an integer m (1 ≤ m ≤ 1000) — the number of words of length n, which Polycarpus knows. The following m lines contain the words themselves — n-letter strings of lowercase Latin letters. All words are distinct.

It is guaranteed that the hidden word appears as one of the given m words. Before the current move Polycarp has told exactly the letters which are currently revealed.

Output

Output the single integer — the number of letters Polycarpus can tell so that the TV show host definitely reveals at least one more letter. It is possible that this number is zero.

Examples

Input

4
a**d
2
abcd
acbd


Output

2


Input

5
lo*er
2
lover
loser


Output

0


Input

3
a*a
2
aaa
aba


Output

1

Note

In the first example Polycarpus can tell letters "b" and "c", which assuredly will be revealed.

The second example contains no letters which can be told as it is not clear, which of the letters "v" or "s" is located at the third position of the hidden word.

In the third example Polycarpus exactly knows that the hidden word is "aba", because in case it was "aaa", then the second letter "a" would have already been revealed in one of previous turns.
import java.io.*;
import java.math.BigInteger;
import java.util.*;


public class Main
{
	private InputStream is;
	private PrintWriter out;
	int time = 0, freq[], start[], end[], dist[], black[], MOD = (int) (1e9 + 7), arr[], weight[][], x[], y[], parent[];
	int MAX = 1000001, N, K;
	long red[], ans = Long.MAX_VALUE;

	ArrayList<Integer>[] amp;
	ArrayList<Pair>[] pmp;
	boolean b[];
	boolean boo[][], b1[];
	Pair prr[];
	HashMap<Pair, Integer> hm = new HashMap();
	int Dp[][] = new int[1100][1100];

	void soln() 
	{
		is = System.in;
		out = new PrintWriter(System.out);
		long s = System.currentTimeMillis();
		solve();

		// out.close();
		out.flush();
		// tr(System.currentTimeMillis() - s + "ms");
	}

	static class ST1 // min ST
	{
		long arr[], st[];
		int size;

		ST1(long a[]) {
			arr = a.clone();
			size = 10 * arr.length;
			st = new long[size];
			build(0, arr.length - 1, 1);
		}

		void build(int ss, int se, int si) {
			if (ss == se) {
				st[si] = arr[ss];
				return;
			}
			int mid = (ss + se) / 2;
			int val = 2 * si;
			build(ss, mid, val);
			build(mid + 1, se, val + 1);
			st[si] = Math.min(st[val], st[val + 1]);
		}

		void update(int ss, int se, int idx, long val, int si) {
			if (ss == se) {
				// if(si==idx+1)
				st[si] = val;
				return;
			}
			int mid = (ss + se) / 2;
			if (ss <= idx && idx <= mid) {
				update(ss, mid, idx, val, 2 * si);
			} else {
				update(mid + 1, se, idx, val, 2 * si + 1);
			}
			int v = 2 * si;
			st[si] = Math.min(st[v], st[v + 1]);
		}

		long get(int ss, int se, int l, int r, int si) {
			if (l > se || r < ss || l > r)
				return Long.MAX_VALUE / 1000;
			if (l <= ss && r >= se)
				return st[si];
			int mid = (ss + se) / 2;
			int val = 2 * si;
			return Math.min(get(ss, mid, l, r, val), get(mid + 1, se, l, r, val + 1));
		}
	}

	public static void main(String[] args) throws Exception
	{
		new Thread(null, new Runnable() 
		{
			public void run() 
			{
				try 
				{
					// new CODEFORCES().soln();
				} catch (Exception e) 
				{
					System.out.println(e);
				}
			}
		}, "1", 1 << 26).start();
		new Main().soln();
	}

	int D[][];
	char ch[][], ch1[];
	int hash = 29;
	int x2, y2;
	HashSet<Integer>[] hs = (HashSet<Integer>[]) new HashSet[110];
	cell[] c;
	Pair[] p = new Pair[4];
	HashSet<String> set = new HashSet<>();
	HashSet<String> dp = new HashSet<>();
	private void solve()
	{
		int n = ni();
		String str = ns();
		int m = ni();
		HashSet<Integer> hs = new HashSet<>();
		for(char c : str.toCharArray()) hs.add(c-'a');
		String[] ss = new String[m];
		for(int i =0 ; i< m; i++) ss[i] = ns();
		boolean b[] = new boolean[26];
		for(char i = 'a'; i<='z';i++) {
			boolean x = false;
			for(int j = 0; j< m; j++) {
				x = false;
				for(int k = 0;k<n;k++) {
					if(ss[j].charAt(k)==i || (str.charAt(k)=='*' && hs.contains(ss[j].charAt(k)-'a') || (str.charAt(k)!='*' && str.charAt(k)!=ss[j].charAt(k)))) {
						x = true;
						break;
					}
				}
				if(!x) break;
			}
			if(x) b[i-'a'] = true;
		}
		int ans =0 ;
		for(int i = 0; i< 26;i++) {
			if(b[i] && !hs.contains(i)) ans++;
		}
		System.out.println(ans);
	}
	void replace(String str, String prev) {
		if(dp.contains(str)) return;
		dp.add(str);
		if(set.contains(str)) {
			return;
		}
		else {
			boolean b = false;
			str = str.replaceFirst("u","oo");
			if(!str.equals(prev)) {
				replace(str, str);
				b = true;
			}
			str = str.replaceFirst("kh","h");
			if(!str.equals(prev)) {
				replace(str, str);
				b = true;
			}
			if(!b) {
				set.add(str);
				return;
			}
		}
	}
	void bfs(int s, int n) {
		b = new boolean[n];
		dist = new int[n];
		Arrays.fill(dist, 1000000);
		dist[s] = 0;
		b[s] = true;
		Queue<Integer> q = new LinkedList<>();
		q.add(s);
		while(!q.isEmpty()) {
			int y = q.poll();
			for(int i : amp[y]) {
				dist[i] = min(dist[i],dist[y]+1);
				if(!b[i]) {
					b[i] = true;
					q.add(i);
				}
			}
		}
	}
	boolean check(String s, String s1) {
		char ch1[] = s.toCharArray(), ch2[] = s1.toCharArray();
		int arr[] = new int[10];
		for(char c : ch1) {
			arr[c-'0']++;
		}
		int ans = 0;
		for(char c:ch2) {
			arr[c-'0']--;
		}
		
		for(int i:arr) ans += ((i>0)?i:0);
		return ans==3;
	}
	void seive(int n)
	{
		start = new int[n];
		for(int i = 2;i<n;i++) {
			if(start[i]==0) {
				for(int j = 2*i;j<n;j+=i) {
					start[j] = i;
				}
			}
		}
	}
	void print(int[][] arr) 
	{
		int seed = 110, n = arr.length - 220;
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				System.out.print(arr[i + seed][j + seed] + " ");
			}
			System.out.println();
		}
		System.out.println();
	}

	 class cell implements Comparable<cell>
	 {
		int s, d, p, i;

		cell(int t, int d, int p, int i) {
			this.s = t;
			this.p = p;
			this.d = d;
			this.i = i;
		}

		public int compareTo(cell other) {
			// return Integer.compare(val, other.val);
			return Long.compare(d, other.d) != 0 ? (Long.compare(d, other.d)): (Long.compare(i,other.i));
											// other.v));//((Long.compare(u, other.u) != 0 ? (Long.compare(u, other.u)):
											// (Long.compare(v, other.v)))
			// &(Long.compare(u, other.v) != 0 ? (Long.compare(u, other.v)):
			// (Long.compare(v, other.u))));
		}

		public String toString() {
			return this.d + " " + this.s +" "+this.p+" "+this.i;
		}
	}

	int abs(int x)
	{
		return ((x > 0) ? x : -x);
	}

	long ret(int p) 
	{
		if (p >= 0)
			return 0;
		else
			return 1;
	}

	long val(int p, int a, int b) 
	{
		if (p >= 0) {
			return (a * 1l * p);
		}
		return (b * 1l * p);
	}

	void ternary_search(int l, int r) 
	{
		// System.out.println(l+" "+r+" "+ans);
		// for(int i : arr) System.out.print(i+" ");
		// System.out.println();
		if (r >= l) {
			int mid1 = l + (r - l) / 3;
			int mid2 = r - (r - l) / 3;
			long cnt1 = 0, cnt2 = 0;
			cnt1 = compute(mid1);
			cnt2 = compute(mid2);
			// System.out.println(mid1+" "+ cnt1+" "+mid2+" "+cnt2);
			ans = Math.min(cnt1, cnt2);
			if (cnt1 < cnt2) {
				ternary_search(l, mid2 - 1);
			} else {
				ternary_search(mid1 + 1, r);
			}
		}
		return;
	}

	long compute(int x) 
	{
		long ans = 0;
		int c = arr[0];
		for (int i = 1; i <= x; i++) {
			ans += max(c + 1 - arr[i], 0);
			c = max(c + 1, arr[i]);
		}
		int temp = arr[x];
		arr[x] = max(c + 1, arr[x]);
		// SSystem.out.println(arr[x]+" "+ans);
		c = arr[arr.length - 1];
		for (int i = arr.length - 1; i > x; i--) {
			ans += max(c + 1 - arr[i - 1], 0);
			c = max(c + 1, arr[i - 1]);
		}
		arr[x] = temp;
		return ans;
	}

	public int getParent(int x) 
	{
		while (parent[x] != x) {
			parent[x] = parent[parent[x]];
			x = parent[x];
		}
		return x;
	}

	void getFactors(int n, int x)
	{
		for (int i = 1; i * i <= n; i++) {
			if (n % i == 0) {
				hs[x].add(i);
				hs[x].add(n / i);
			}
		}
	}

	void recur(int a, int b, int k) 
	{
		if (k == 0) {
			if (a == x2 && b == y2)
				ans++;
			return;
		}
		recur(a, b + 1, k - 1);
		recur(a, b - 1, k - 1);
		recur(a + 1, b, k - 1);
		recur(a - 1, b, k - 1);
	}

	int min(int a, int b) 
	{
		return (a < b) ? a : b;
	}

	/*private class Cell implements Comparable<Cell> {
		int u, v, s;

		public Cell(int u, int v, int s) {
			this.u = u;
			this.v = v;
			this.s = s;
		}

		public int hashCode() {
			return Objects.hash();
		}

		public int compareTo(Cell other) {
			return (Long.compare(s, other.s) != 0 ? (Long.compare(s, other.s))
					: (Long.compare(v, other.v) != 0 ? Long.compare(v, other.v) : Long.compare(u, other.u)))
					& ((Long.compare(s, other.s) != 0 ? (Long.compare(s, other.s))
							: (Long.compare(u, other.v) != 0 ? Long.compare(u, other.v) : Long.compare(v, other.u))));
		}

		public String toString() {
			return this.u + " " + this.v;
		}
	}*/

	class Pair implements Comparable<Pair>
	{
		int u ,v,i;

		Pair(int u, int v) {
			this.u = u;
			this.i = v;
		}

		Pair(int u, int v, int i) {
			this.u = u;
			this.v = v;
			this.i = i;
		}

		public int hashCode() {
			return Objects.hash();
		}

		public boolean equals(Object o) {
			Pair other = (Pair) o;
			return ((u == other.u && v == other.v));
		}

		public int compareTo(Pair other) {
			// return Integer.compare(val, other.val);
			return Long.compare(u, other.u) != 0 ? (Long.compare(u, other.u)) : (Long.compare(i, other.i));// ((Long.compare(u,
		
		}									
		public String toString() {
			return this.u + " " + this.v +" "+this.i;
		}
	}

	int max(int a, int b) 
	{
		if (a > b)
			return a;
		return b;
	}

	static class FenwickTree 
	{

		int[] array; // 1-indexed array, In this array We save cumulative
						// information to perform efficient range queries and
						// updates

		public FenwickTree(int size) {
			array = new int[size + 1];
		}

		public int rsq(int ind) {
			assert ind > 0;
			int sum = 0;
			while (ind > 0) {
				sum += array[ind];
				// Extracting the portion up to the first significant one of the
				// binary representation of 'ind' and decrementing ind by that
				// number
				ind -= ind & (-ind);
			}
			return sum;
		}

		public int rsq(int a, int b) {
			assert b >= a && a > 0 && b > 0;
			return rsq(b) - rsq(a - 1);
		}

		public void update(int ind, int value) {
			assert ind > 0;
			while (ind < array.length) {
				array[ind] += value;
				// Extracting the portion up to the first significant one of the
				// binary representation of 'ind' and incrementing ind by that
				// number
				ind += ind & (-ind);
			}
		}

		public int size() {
			return array.length - 1;
		}
	}

	void buildGraph(int n)
	{
		for (int i = 0; i < n; i++) {
			int x1 = ni(), y1 = ni(), z = ni();
			//pmp[x1].add(new Pair(y1, z));
		}
	}

	long modInverse(long a, long mOD2)
	{
		return power(a, mOD2 - 2, mOD2);
	}

	long power(long x, long y, long m) 
	{
		if (y == 0)
			return 1;
		long p = power(x, y / 2, m) % m;
		p = (p * p) % m;

		return (y % 2 == 0) ? p : (x * p) % m;
	}

	public long gcd(long a, long b)
	{
		if (b == 0)
			return a;
		return gcd(b, a % b);
	}

	static class ST 
	{
		int arr[], lazy[], n;

		ST(int a) {
			n = a;
			arr = new int[10 * n];
			lazy = new int[10 * n];
		}

		void up(int l, int r, int val) {
			update(0, n - 1, 0, l, r, val);
		}

		void update(int l, int r, int c, int x, int y, int val) {
			if (lazy[c] != 0) {
				lazy[2 * c + 1] += lazy[c];
				lazy[2 * c + 2] += lazy[c];
				if (l == r)
					arr[c] += lazy[c];
				lazy[c] = 0;
			}
			if (l > r || x > y || l > y || x > r)
				return;
			if (x <= l && y >= r)

			{
				lazy[c] += val;
				return;
			}
			int mid = l + r >> 1;
			update(l, mid, 2 * c + 1, x, y, val);
			update(mid + 1, r, 2 * c + 2, x, y, val);
			arr[c] = Math.max(arr[2 * c + 1], arr[2 * c + 2]);
		}

		int an(int ind) {
			return ans(0, n - 1, 0, ind);
		}

		int ans(int l, int r, int c, int ind) {
			if (lazy[c] != 0) {
				lazy[2 * c + 1] += lazy[c];
				lazy[2 * c + 2] += lazy[c];
				if (l == r)
					arr[c] += lazy[c];
				lazy[c] = 0;
			}
			if (l == r)
				return arr[c];
			int mid = l + r >> 1;
			if (mid >= ind)
				return ans(l, mid, 2 * c + 1, ind);
			return ans(mid + 1, r, 2 * c + 2, ind);
		}
	}

	public static int[] shuffle(int[] a, Random gen)
	{
		for (int i = 0, n = a.length; i < n; i++) {
			int ind = gen.nextInt(n - i) + i;
			int d = a[i];
			a[i] = a[ind];
			a[ind] = d;
		}
		return a;
	}

	long power(long x, long y, int mod)
	{
		long ans = 1;
		while (y > 0) {
			if (y % 2 == 0) {
				x = (x * x) % mod;
				y /= 2;
			} else {
				ans = (x * ans) % mod;
				y--;
			}
		}
		return ans;
	}

	// To Get Input
	// Some Buffer Methods
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;

	private int readByte() 
	{
		if (lenbuf == -1)
			throw new InputMismatchException();
		if (ptrbuf >= lenbuf) {
			ptrbuf = 0;
			try {
				lenbuf = is.read(inbuf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (lenbuf <= 0)
				return -1;
		}
		return inbuf[ptrbuf++];
	}

	private boolean isSpaceChar(int c) {
		return !(c >= 33 && c <= 126);
	}

	private int skip() {
		int b;
		while ((b = readByte()) != -1 && isSpaceChar(b))
			;
		return b;
	}

	private double nd() {
		return Double.parseDouble(ns());
	}

	private char nc() {
		return (char) skip();
	}

	private String ns() {
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != '
									// ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	private char[] ns(int n) {
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while (p < n && !(isSpaceChar(b))) {
			buf[p++] = (char) b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}

	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for (int i = 0; i < n; i++)
			map[i] = ns(m);
		return map;
	}

	private int[] na(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = ni();
		return a;
	}

	private int ni() {
		int num = 0, b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}

		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}

	private long nl() {
		long num = 0;
		int b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}

		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}

	private boolean oj = System.getProperty("ONLINE_JUDGE") != null;

	private void tr(Object... o) {
		if (!oj)
			System.out.println(Arrays.deepToString(o));
	}
}