You are given three strings A, B and C. Each of these is a string of length N consisting of lowercase English letters.

Our objective is to make all these three strings equal. For that, you can repeatedly perform the following operation:

* Operation: Choose one of the strings A, B and C, and specify an integer i between 1 and N (inclusive). Change the i-th character from the beginning of the chosen string to some other lowercase English letter.



What is the minimum number of operations required to achieve the objective?

Constraints

* 1 \leq N \leq 100
* Each of the strings A, B and C is a string of length N.
* Each character in each of the strings A, B and C is a lowercase English letter.

Input

Input is given from Standard Input in the following format:


N
A
B
C


Output

Print the minimum number of operations required.

Examples

Input

4
west
east
wait


Output

3


Input

9
different
different
different


Output

0


Input

7
zenkoku
touitsu
program


Output

13
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int n = sc.nextInt();
		String[] s1 = sc.nextLine().split("");
		String[] s2 = sc.nextLine().split("");
		String[] s3 = sc.nextLine().split("");
		int ans = 0;
		for (int i = 0; i < n; i++) {
			if(s2[i].charAt(0) != s3[i].charAt(0))
				ans++;
			if(s1[i].charAt(0) != s2[i].charAt(0) && s1[i].charAt(0) != s3[i].charAt(0))
				ans++;
		}
		System.out.println(ans);
	}


}

class Scanner {
	StringTokenizer st;
	BufferedReader br;

	public Scanner(InputStream system) {
		br = new BufferedReader(new InputStreamReader(system));
	}

	public String next() throws IOException {
		while (st == null || !st.hasMoreTokens())
			st = new StringTokenizer(br.readLine());
		return st.nextToken();
	}

	public String nextLine() throws IOException {
		return br.readLine();
	}

	public int nextInt() throws IOException {
		return Integer.parseInt(next());
	}

	public double nextDouble() throws IOException {
		return Double.parseDouble(next());
	}

	public char nextChar() throws IOException {
		return next().charAt(0);
	}

	public Long nextLong() throws IOException {
		return Long.parseLong(next());
	}

	public boolean ready() throws IOException {
		return br.ready();
	}

	public void waitForInput() throws InterruptedException {
		Thread.sleep(3000);
	}

}
