Codeforce 653A 小熊的小球（不是难题，但麻烦）

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本文介绍了一个有趣的编程问题——礼物球问题。题目要求从给定的球中选择三个大小不同的球赠送给三位朋友，并确保任意两个球的大小相差不超过2。文章提供了一段C++代码示例，展示了如何通过排序和遍历数组来解决这个问题。

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Limak is a little polar bear. He has n balls, the i-th ball has size t_i.

Limak wants to give one ball to each of his three friends. Giving gifts isn't easy — there are two rules Limak must obey to make friends happy:

No two friends can get balls of the same size.
No two friends can get balls of sizes that differ by more than 2.

For example, Limak can choose balls with sizes 4, 5 and 3, or balls with sizes 90,91 and 92. But he can't choose balls with sizes 5, 5 and 6 (two friends would get balls of the same size), and he can't choose balls with sizes 30, 31 and 33 (because sizes 30 and 33 differ by more than 2).

Your task is to check whether Limak can choose three balls that satisfy conditions above.

Input

The first line of the input contains one integer n (3 ≤ n ≤ 50) — the number of balls Limak has.

The second line contains n integers t₁, t₂, ..., t_n (1 ≤ t_i ≤ 1000) where t_i denotes the size of the i-th ball.

Output

Print "YES" (without quotes) if Limak can choose three balls of distinct sizes, such that any two of them differ by no more than 2. Otherwise, print "NO" (without quotes).

Examples

Input

4
18 55 16 17

Output

YES

Input

6
40 41 43 44 44 44

Output

NO

Input

8
5 972 3 4 1 4 970 971

Output

YES

Note

In the first sample, there are 4 balls and Limak is able to choose three of them to satisfy the rules. He must must choose balls with sizes 18, 16 and 17.

In the second sample, there is no way to give gifts to three friends without breaking the rules.

In the third sample, there is even more than one way to choose balls:

Choose balls with sizes 3, 4 and 5.
Choose balls with sizes 972, 970, 971.

题意：很简单，给定集合，假如含有连续三个整数，如（13,14,15）并且13,14,15的数量都不大于2，输出yes;否则输出no;

#include<bits/stdc++.h>
using namespace std;
int a[100];
int z[100];
int x[100];
int q[100];
struct sec{
	int b,c,d;
};
int main(){
	int n,g=0;
	cin>>n;
	vector<sec> v;
	sec r;
	memset(z,0,sizeof(z));
	memset(x,0,sizeof(x));
	memset(q,0,sizeof(q));
	for(int i=0;i<n;i++)
    {
	   cin>>a[i];
    }
	 sort(a,a+n);
    int m=unique(a,a+n)-a;
    for(int i=0;i<=m-3;i++)
    {
	 	if(a[i+1]-a[i]==1&&a[i+2]-a[i+1]==1)
	 	{
		  r.b=a[i];
		  r.c=a[i+1];
		  r.d=a[i+2];
		  v.push_back(r);
		  g=1;
	    }
    }
     for(int i=m+1;i<n;i++)
	 {
     	for(int j=0;j<v.size();j++)
     		{
			 if(a[i]==v[j].b)
			   z[i]++;
		    if(a[i]==v[j].c)
			   x[i]++;
	        if(a[i]==v[j].d)
			   q[i]++;
	        }
	}
	  int ff=0;
	  for(int i=0;i<100;i++)
	  if(z[i]>1||x[i]>1||q[i]>1)
	  ff=1;
	  if(g==1&&ff==0)
	  cout<<"YES"<<endl;
	  else
	  cout<<"NO"<<endl;

	return 0;
}