One day Jeff got hold of an integer sequence a1, a2, ..., an of length n. The boy immediately decided to analyze the sequence. For that, he needs to find all values of x, for which these conditions hold:

  * x occurs in sequence a. 
  * Consider all positions of numbers x in the sequence a (such i, that ai = x). These numbers, sorted in the increasing order, must form an arithmetic progression. 



Help Jeff, find all x that meet the problem conditions.

Input

The first line contains integer n (1 ≤ n ≤ 105). The next line contains integers a1, a2, ..., an (1 ≤ ai ≤ 105). The numbers are separated by spaces.

Output

In the first line print integer t — the number of valid x. On each of the next t lines print two integers x and px, where x is current suitable value, px is the common difference between numbers in the progression (if x occurs exactly once in the sequence, px must equal 0). Print the pairs in the order of increasing x.

Examples

Input

1
2


Output

1
2 0


Input

8
1 2 1 3 1 2 1 5


Output

4
1 2
2 4
3 0
5 0

Note

In the first test 2 occurs exactly once in the sequence, ergo p2 = 0.
import java.io.*;
import java.util.*;

public class solution {
    static class sort implements Comparator<ArrayList<Integer>> {

        @Override
        public int compare(ArrayList<Integer> o1, ArrayList<Integer> o2) {
            int c = o2.get(1).compareTo(o1.get(1));
            if (c == 0) {

                c = o2.get(0).compareTo(o1.get(0));
            }
            return c;
        }
    }

    public static void merge(long arr[], int l, int m, int r) {
        int n1 = m - l + 1;
        int n2 = r - m;
        long L[] = new long[n1];
        long R[] = new long[n2];
        for (int i = 0; i < n1; ++i)
            L[i] = arr[l + i];
        for (int j = 0; j < n2; ++j)
            R[j] = arr[m + 1 + j];
        int i = 0, j = 0;
        int k = l;
        while (i < n1 && j < n2) {
            if (L[i] <= R[j]) {
                arr[k] = L[i];
                i++;
            } else {
                arr[k] = R[j];
                j++;
            }
            k++;
        }
        while (i < n1) {
            arr[k] = L[i];
            i++;
            k++;
        }
        while (j < n2) {
            arr[k] = R[j];
            j++;
            k++;
        }
    }

    public static void sort(long arr[], int l, int r) {
        if (l < r) {
            int m = (l + r) / 2;
            sort(arr, l, m);
            sort(arr, m + 1, r);
            merge(arr, l, m, r);
        }
    }

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

    public static long lcm(long a, long b) {
        long gcd = gcd(a, b);
        long pord = a * b;
        return pord / gcd;
    }

    static class graphs {
        private int V;
        private ArrayList<Integer> adj[];

        graphs(int v) {
            V = v;
            adj = new ArrayList[v];
            for (int i = 0; i < v; i++) {
                adj[i] = new ArrayList<>();
            }
        }

        void addedge(int u, int v) {
            adj[u].add(v);
        }

        void BFS(int v) {
            boolean visited[] = new boolean[V];
            Queue<Integer> Q = new LinkedList<>();
            visited[v] = true;
            Q.add(v);
            while (!Q.isEmpty()) {
                int temp = Q.peek();
                System.out.print(temp + " ");
                Q.remove();
                Iterator<Integer> it = adj[temp].listIterator();
                while (it.hasNext()) {
                    int n = it.next();
                    if (!visited[n]) {
                        visited[n] = true;
                        Q.add(n);
                    }
                }
            }
        }

        void DFSUtil(int v, boolean visited[]) {
            visited[v] = true;
            System.out.print(v + " ");
            Iterator<Integer> it = adj[v].listIterator();
            while (it.hasNext()) {
                int n = it.next();
                if (!visited[n]) {
                    DFSUtil(n, visited);
                }
            }
        }

        void DFS(int v) {
            boolean visited[] = new boolean[V];
            DFSUtil(v, visited);
        }
    }

    public static int Binaraysearch(long a[], int low, int high, long key) {
        while (low <= high) {
            int mid = low + (high - low) / 2;
            if (a[mid] == key) {
                return mid;
            } else if (a[mid] < key) {
                low = mid;
            } else {
                high = mid;
            }
        }
        return -1;
    }

    public static void seive(boolean prime[]) {
        Arrays.fill(prime, true);
        int n = prime.length - 1;
        for (int p = 2; p * p <= n; p++) {
            if (prime[p] == true) {
                for (int i = p * p; i <= n; i += p)
                    prime[i] = false;
            }
        }
    }

    public static boolean random(long a, long b) {
        return a < b;
    }

    public static int subArraySum(int arr[], int n, int sum) {
        int curr_sum = arr[0], start = 0, i;
        for (i = 1; i <= n; i++) {
            // If curr_sum exceeds the sum, then remove the starting elements
            while (curr_sum > sum && start < i - 1) {
                curr_sum = curr_sum - arr[start];
                start++;
            }

            // If curr_sum becomes equal to sum, then return true
            if (curr_sum == sum) {
                int p = i - 1;
                if (p != start)
                    return 1;
            }

            // Add this element to curr_sum
            if (i < n)
                curr_sum = curr_sum + arr[i];

        }
        return 0;
    }
    static class pair{
        int x;
        int dis;
        public pair(int x,int dis) {
            this.x = x;
            this.dis = dis;
        }
    }
    public static class InputReader {
        private final InputStream stream;
        private final byte[] buf = new byte[8192];
        private int curChar, snumChars;

        public InputReader(InputStream st) {
            this.stream = st;
        }

        public int read() {
            if (snumChars == -1)
                throw new InputMismatchException();
            if (curChar >= snumChars) {
                curChar = 0;
                try {
                    snumChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (snumChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public int[] nextIntArray(int n) {
            int a[] = new int[n];
            for (int i = 0; i < n; i++) {
                a[i] = nextInt();
            }
            return a;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public String nextLine() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isEndOfLine(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        private boolean isEndOfLine(int c) {
            return c == '\n' || c == '\r' || c == -1;
        }
    }
    public static void main(String args[]) throws IOException {
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);
        int n = in.nextInt();
        int a[] = new int[n];
        for(int i=0;i<n;i++){
            a[i] = in.nextInt();
        }
        TreeMap<Integer,pair>H = new TreeMap<>();
        for(int i=0;i<n;i++){
            if(H.containsKey(a[i])){
                pair p = H.get(a[i]);
                if(p.dis == 0){
                    int y = i-p.x;
                    p.dis = y;
                    p.x = i;
                }
                else if(H.get(a[i]).dis!=-1){
                    int y = i-p.x;
                    if(y == p.dis){
                        p.x = i;
                    }
                    else{
                        p.dis = -1;
                    }
                }
            }
            else{
                H.put(a[i],new pair(i,0));
            }
        }
        int count = 0;
        for(Integer s:H.keySet()){
            if(H.get(s).dis==-1)
                count++;
        }
        out.println(H.size()-count);
        for(Integer s: H.keySet()){
            if(H.get(s).dis!=-1)
            out.println(s + " " + H.get(s).dis);
        }
        out.flush();
    }
}