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.
//package clipse;


import java.util.*;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Random;
import java.util.StringTokenizer;
import java.io.*;
import java.math.*;




public class AA
{
	
	static StringBuilder sb;
	static dsu dsu;
	static long fact[];
	static int mod=998244353;
	static long A[][];
	static long ans[];
	static int n;
	
	
	static void solve()
    {
		int A[]=new int[100000+1];
		Arrays.fill(A, -1);
		HashMap<Integer,ArrayList<Integer>>h=new HashMap<>();
		int n=i();
		for(int i=0;i<n;i++)
		{
			int x=i();
			ArrayList<Integer>l=h.getOrDefault(x, new ArrayList<>());
			l.add(i);
			h.put(x,l);
			
		}
		int get=0;
		for(Map.Entry mp:h.entrySet())
		{
			int key=(int)mp.getKey();
			ArrayList<Integer>l=(ArrayList)mp.getValue();
			int dif=-1;
			if(l.size()==1)
			{
				dif=0;
				get++;
			}
			else if(l.size()==2)
			{
				dif=l.get(1)-l.get(0);
				get++;
			}
			else
			{
				
				
				int d=l.get(1)-l.get(0);
				int f=0;
				for(int i=1;i<l.size();i++)
				{
					if(l.get(i)-l.get(i-1)!=d)
					{
						f=-1;
					}
				}
				if(f==-1)
					dif=-1;
				else {
					dif=d;
					get++;
				}
				
				
			}
			A[key]=dif;
			
					
			
		}
		sb.append(get+"\n");
		for(int i=0;i<A.length;i++)
		{
			if(A[i]!=-1)
			{
				sb.append(i+" "+A[i]+"\n");
			}
		}
		
		
		
		
    }
	
	
	
	
	 public static void main(String[] args)
	 {
	         sb=new StringBuilder();
	         
	       /*  fact=new long[(int)1e6+1];
	         fact[0]=fact[1]=1;
	         for(int i=2;i<fact.length;i++)
	         {
	        	fact[i]=((long)(i%mod)*1L*(long)(fact[i-1]%mod))%mod; 
	         }*/
	        int test=1;
	        while(test-->0) 
	        {
	        	
	    		
	        	 solve();
	        }
	        
	         System.out.println(sb);
	         
	 }
	 
//*******************************************NCR%P*******************************************************	 
	 static long ncr(int n, int r)
	 {
		 if(r>n)
			 return (long)0;
		 
		 long res=fact[n]%mod;
		 //System.out.println(res);
		 res=((long)(res%mod)*(long)(p(fact[r],mod-2)%mod))%mod;
		 res=((long)(res%mod)*(long)(p(fact[n-r],mod-2)%mod))%mod;
		 //System.out.println(res);
		 return res;
		
		 
	 }
		static long p(long x, long y)//POWER FXN //
		{
			if(y==0)
				return 1;
			
			long res=1;
			while(y>0)
			{
				if(y%2==1)
				{
					res=(res*x)%mod;
					y--;
				}
				
				x=(x*x)%mod;
				y=y/2;
				
				
			}
			return res;
		}
		

//*******************************************END*******************************************************
	 
	 
	 
	 
	 
	 //*********************************Disjoint set union*************************//
	 static class dsu
	 {
		 int parent[];
		 dsu(int n)
		 {
			 parent=new int[n];
			 for(int i=0;i<n;i++)
				 parent[i]=-1;
		 }
		 int find(int a)
		 {
			 if(parent[a]<0)
				 return a;
			 else
			 {
				 int x=find(parent[a]);
				 parent[a]=x;
				 return x;
			 }
		 }
		 void merge(int a,int b)
		 {
			 a=find(a);
			 b=find(b);
			 if(a==b)
				 return;
			 parent[b]=a;
		 }
	 }
	 
	 
	 
//*******************************************PRIME FACTORIZE *****************************************************************************************************//
	 static TreeMap<Integer,Integer> prime(long n)
	 {
		 TreeMap<Integer,Integer>h=new TreeMap<>();
		 long num=n;
		 for(int i=2;i<=Math.sqrt(num);i++)
		 {
			 if(n%i==0)
			 {
				 int nt=0;
				 while(n%i==0) {
					 n=n/i;
					 nt++;
				 }
				 h.put(i, nt);
			 }
		 }
		 if(n!=1)
			 h.put((int)n, 1);
		 return h;
		 
	 }
	 
	
	
//*************CLASS PAIR ***********************************************************************************************************************************************
	    static class pair implements Comparable<pair>
	    {
	        int x;
	        int y;

	        pair(int x, int y) {
	            this.x = x;
	            this.y = y;
	        }
	        public int compareTo(pair o)
	        {
	        	return y-o.y;
	        	
	        }
			
	       
	    }
//*************CLASS PAIR *****************************************************************************************************************************************************
	
	
	

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        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 int Int() {
            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 String String() {
            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 String();
        }

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

    static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void print(Object... objects) {
            for (int i = 0; i < objects.length; i++) {
                if (i != 0)
                    writer.print(' ');
                writer.print(objects[i]);
            }
        }

        public void printLine(Object... objects) {
            print(objects);
            writer.println();
        }

        public void close() {
            writer.close();
        }

        public void flush() {
            writer.flush();
        }
    }

    static InputReader in = new InputReader(System.in);
    static OutputWriter out = new OutputWriter(System.out);
   

    public static int[] sort(int[] a) {
        int n = a.length;
        ArrayList<Integer> l = new ArrayList<>();
        for (int i : a)
            l.add(i);
        Collections.sort(l);
        for (int i = 0; i < l.size(); i++)
            a[i] = l.get(i);
        return a;
    }

    public static long pow(long x, long y) {
        long res = 1;
        while (y > 0) {
            if (y % 2 != 0) {
                res = (res * x);// % modulus;
                y--;

            }
            x = (x * x);// % modulus;
            y = y / 2;
        }
        return res;
    }
//GCD___+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    public static long gcd(long x, long y) {
        if (x == 0)
            return y;
        else
            return gcd(y % x, x);
    }
    //****************LOWEST COMMON MULTIPLE   *************************************************************************************************************************************

    public static long lcm(long x, long y) {
        return (x * (y / gcd(x, y)));
    }
//INPUT PATTERN******************************************************************************************************************************************************************
    public static int i() {
        return in.Int();
    }

    public static long l() {
        String s = in.String();
        return Long.parseLong(s);
    }

    public static String s() {
        return in.String();
    }

    public static int[] readArray(int n) {
        int A[] = new int[n];
        for (int i = 0; i < n; i++) {
            A[i] = i();
        }
        return A;
    }

    public static long[] readArray(long n) {
        long A[] = new long[(int) n];
        for (int i = 0; i < n; i++) {
            A[i] = l();
        }
        return A;
    }

}






	