CodeForces 653 A. Bear and Three Balls

Description

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

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, 5and 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 33differ
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, ..., tn (1 ≤ ti ≤ 1000)
where ti 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).

Sample Input

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
题意：送三个球给朋友，这三个球最大差值不能超过2，但大小也不能一样，

思路：排序后去重；

代码如下：

#include<stdio.h>
#include<iostream>
#include<algorithm>
using namespace std;
int main()
{
int a[1010];
int n;
while(scanf("%d",&n)!=EOF)
{
int i;
for(i=1;i<=n;i++)
{
scanf("%d",&a[i]);
}
sort(a+1,a+n+1);
int x=unique(a+1,a+1+n)-(a+1);
bool l=true;
for(i=1;i<=x-2;i++)
{
if(a[i+2]-a[i]<=2)
{
printf("YES\n");
l=false;
break;
}

}
if(l==true)
printf("NO\n");
}
}