找三个大小连续的数

Time Limit:2000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u

Submit Status

Description

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, 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 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).

Sample Input

Input

418 55 16 17

Output

YES

Input

640 41 43 44 44 44

Output

NO

Input

85 972 3 4 1 4 970 971

Output

YES

解题思路：这道题思路很简单，找三个数，不能重复，任意两个数的差不能超过2，也就是这组数中要存在三个大小相邻的数。

代码：

#include<stdio.h>int main(){int n,i,j;int flag1,flag2;int a[1001];while(scanf("%d",&n)!=EOF){int flag=0;for(i=0;i<n;i++){scanf("%d",&a[i]);}for(i=0;i<n;i++){ flag1=0,flag2=0;for(j=0;j<n;j++){if(a[j]-1==a[i]){flag1=1;continue;}if(a[j]-2==a[i]){flag2=1;continue;}}if(flag1==1&&flag2==1)flag=1;}if(flag==1)printf("YES\n");elseprintf("NO\n") ;}return 0; }