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.
//    A Computer is Like a mischievous genie.
//    It will give you exactly what you ask for,
//    but not always what you want
//    A code by Rahul Verma


import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Set;
import java.util.SortedSet;
import java.util.Spliterator.OfPrimitive;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;
import javax.print.attribute.HashAttributeSet;
import javax.swing.plaf.nimbus.AbstractRegionPainter;


public class Main {



  public static PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));

  static class FastReader {

    BufferedReader br;
    StringTokenizer st;

    public FastReader() {
      br = new BufferedReader(new
          InputStreamReader(System.in));
    }

    String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    }

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

    long nextLong() {
      return Long.parseLong(next());
    }

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

    String[] nextSArray() {
      String sr[] = null;
      try {
        sr = br.readLine().trim().split(" ");
      } catch (IOException e) {
        e.printStackTrace();
      }
      return sr;
    }

    String nextLine() {
      String str = "";
      try {
        str = br.readLine();
      } catch (IOException e) {
        e.printStackTrace();
      }

      return str;
    }
  }


  static long powmodulo(long a, long p) {
    if (p == 0)
      return 1 % mod;
    if (p == 1)
      return a % mod;
    long ans = 1;
    while (p > 0) {
      if ((p & 1) > 0) {
        ans = (ans * a) % mod;
      }
      a = (a * a) % mod;
      p = p >> 1;
    }
    return ans % mod;
  }




  static long mod = 1000000007;

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

  static long fast_powerNumbers(long a,long n)
  {
    if(n==1)
      return a;
    long ans=fast_powerNumbers(a,n/2);
    if(n%2==0)
      return (ans*ans);
    else
      return ((ans*ans)*(a));
  }



  static void dfs_helper(int [][] arr,int i,int j,int team,int n,int m)
  {
    arr[i][j]=team;
    if(i-1>=0 && arr[i-1][j]==1)
      dfs(arr,i-1,j,team,n,m);
    if(j-1>=0 && arr[i][j-1]==1)
      dfs(arr,i,j-1,team,n,m);
    if(i+1< n && arr[i+1][j]==1)
      dfs(arr,i+1,j,team,n,m);
    if(j+1<m && arr[i][j+1]==1)
      dfs(arr,i,j+1,team,n,m);

  }

  static boolean haveCycle=false;
  static int visited[];
  static HashMap<Integer,ArrayList<Integer>>hm;
  static int parent[];

  static void bfs(int n)
  {
    parent=new int[n];
    Queue<Integer>qu=new LinkedList<>();
    qu.add(0);
    parent[0]=-1;
    visited[0]=1;
    boolean cycle=false;
    while (!qu.isEmpty())
    {
      int node=qu.remove();
     cycle=false;

      for (Integer nbr:hm.get(node)
      ) {
        if(visited[nbr]==0)
        {
          visited[nbr]=visited[node]+1;
          parent[nbr]=node;
          qu.add(nbr);
        }
        else
        {
          if(nbr!=parent[node]&&((visited[node]+1)-visited[nbr])%2==1)
          {cycle=true;break;}


        }
      }
    }
    haveCycle=cycle;

  }

  static void dfs(int [][] arr,int i,int j,int team,int n,int m)
  {
        dfs_helper(arr,i,j,team,n,m);

  }





    public static void main(String[] args) throws Exception {
    FastReader sc = new FastReader();

//    int t1=sc.nextInt();
//      for (int t = 0; t < t1 ; t++) {

        int n=sc.nextInt();
        TreeMap<Integer,Pair>hm=new TreeMap<>();
      for (int i = 0; i < n; i++) {
        int ele=sc.nextInt();



        if(hm.containsKey(ele))
        {
          if(hm.get(ele).b==-2)
            continue;

          if(hm.get(ele).b==0)
          {
            int last=hm.get(ele).a;
            hm.put(ele,new Pair(i,i-last));
          }
          else
          {
            int diff = hm.get(ele).b;
            int last=hm.get(ele).a;
            if(i-last==diff)
            {
              hm.put(ele,new Pair(i,diff));
            }
            else
            {
              hm.put(ele,new Pair(-2,-2));
            }
          }
        }
        else
        {
          hm.put(ele,new Pair(i,0));
        }

      }
      int ans=0;
      for (Integer a:hm.keySet()
      ) {
        if(hm.get(a).b!=-2)
        {++ans;}
      }
      out.println(ans);
      for (Integer a:hm.keySet()
      ) {
        if(hm.get(a).b!=-2)
        {out.println(a+" "+hm.get(a).b);}
      }
      out.close();
    }}


class DSU
{
  int parent[],rank[];
  DSU(int n)
  {
    parent=new int[n];
    rank=new int[n];
    for (int i = 0; i <n ; i++) {
      parent[i]=-1;
      rank[i]=1;
    }
  }

  int find(int s1)
  {
    if(parent[s1]==-1)
      return s1;

    parent[s1]=find(parent[s1]);
    return parent[s1];
  }

  void unite(int s1,int s2)
  {

    int p1 = find(s1);
    int p2=find(s2);
    if(rank[s1]>rank[s2])
    {
      parent[p2]=find(p1);
      rank[p1]+=rank[p2];
    }else
    {
      parent[p1]=p2;
      rank[p2]+=rank[p1];
    }
  }

}

class Pair
{
  int a; int b;
  Pair(int a,int b)
  {
    this.a=a;
    this.b=b;
  }
}


class Graph
{
  HashMap<Integer,ArrayList<Integer>>hm;
  Graph()
  {
    hm=new HashMap<>();
  }
  Graph(int n){

    hm=new HashMap<>();
    for (int i = 0; i <n ; i++) {
      hm.put(i,new ArrayList<Integer>());
    }
  }
  // function for adding an edge.................................................
  public void addEdge(int a,int b,boolean isDir)
  {
    if(isDir)
    {
      if(hm.containsKey(a))
      {
        hm.get(a).add(b);
      }
      else
      {
        hm.put(a,new ArrayList<>(Arrays.asList(b)));
      }
    }
    else
    {
      if(hm.containsKey(a))
      {
        hm.get(a).add(b);
      }
      else if(!hm.containsKey(a))
      {
        hm.put(a,new ArrayList<>(Arrays.asList(b)));
      }

      if(hm.containsKey(b))
      {
        hm.get(b).add(a);
      }
      else if(!hm.containsKey(b))
      {
        hm.put(b,new ArrayList<>(Arrays.asList(a)));
      }
    }
  }

  public void addWeightededge(){

}



}

// out.println(al.toString().replaceAll("[\\[|\\]|,]",""));

