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.util.*;
import java.io.*;
//@ Author :: Abhimanyu Chauhan
public class B_352 implements Runnable{
    
    public void solve(){
        int n= scan.nextInt();
        int ar[] = scan.nia(n);
        int N = (int)1e5+1;
        int dif[] = new int[N];
        int prev[] =new int[N];
        Set<Integer> del = new HashSet<>();
        Arrays.fill(prev,-1);
        Arrays.fill(dif,-1);
        for(int i=0;i<n;i++){
            if(dif[ar[i]]==0 && prev[ar[i]]!=-1){
                dif[ar[i]] = i-prev[ar[i]];
                prev[ar[i]] = i;
            }else if(prev[ar[i]]==-1){
                prev[ar[i]] = i;
                dif[ar[i]]= 0;
            }else if(dif[ar[i]]!=-1 && prev[ar[i]]!=-1){
                int k = i - prev[ar[i]];
                if(dif[ar[i]]!=k){del.add(ar[i]);}
                else prev[ar[i]] = i;
            }
            // out.println("p[1] : "+prev[1]);
        }
        int count = 0;
        StringBuilder sb = new StringBuilder();
        for(int i =  0;i<N;i++){
            if(!del.contains(i) && dif[i]!=-1){
                count++;
                sb.append(i+ " "+dif[i]).append("\n");
            }
        }
        out.print(count+"\n"+sb.toString());
    }
    
    InputReader scan;
    PrintWriter out;
    
    @Override
    public void run(){
        scan = new InputReader(System.in);
        out = new PrintWriter(System.out);
        solve();
        out.flush();
        out.close();
    }
    
    public static void main(String[] args) {
        new Thread(null,new B_352(),"Main",1<<26).start();
    }
    
    
    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
        private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        public InputReader(InputStream stream) {
            this.stream = stream;
        }
        
        public int read() {
            if (numChars==-1) 
                throw new InputMismatchException();
            
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                }
                catch (IOException e) {
                    throw new InputMismatchException();
                }
                
                if(numChars <= 0)               
                    return -1;
            }
            return buf[curChar++];
        }
     
        public String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
        public int nextInt() {
            int c = read();
            
            while(isSpaceChar(c)) 
                c = read();
            
            int sgn = 1;
            
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            
            int res = 0;
            do {
                if(c<'0'||c>'9') 
                    throw new InputMismatchException();
                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 {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
                return res * sgn;
        }
        
        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }
        
        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 boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
     
        public String next() {
            return readString();
        }
        
        public long[] nla(int n){ //nextLongArray()
            long ar[] = new long[n];
            for(int i=0;i<n;i++){
                ar[i] = this.nextLong();
            }
            return ar;
        }

        public int[] nia(int n){
            int ar[] = new int[n];
            for(int i=0;i<n;i++){
                ar[i] = this.nextInt();
            }
            return ar;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

}