【codeforces】Bear and Three Balls

た入场券 2022-07-16 23:42 182阅读 0赞

A. Bear and Three Balls

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

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 *t*1, *t*2, ..., *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

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, 16and 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:

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

其实我这个方法是麻烦了，其实还可以更简单，比如，输入时标记一下，如果以前输入过了就不再入数组，还有一个去重函数unique也行。

#include<cstdio>
    #include<iostream>
    #include<algorithm>
    using namespace std;
    const int N = 55;
    int a[N];
    int main() {
    	int n;
    	while(scanf("%d",&n)!=EOF) {
    		for(int i=0; i<n; i++) {
    			scanf("%d",&a[i]);
    		}
    		sort(a,a+n);
    		int flag=0;
    		int count=0;
    		for(int i=0; i<=n-3; i++) {
    			count=0;
    			int cnt=a[i];
    			for(int j=i+1; j<n; j++) {
    				if(a[j]==cnt+1) {
    					count++;
    					cnt=a[j];
    				} else if(a[j]==cnt) {
    					continue;
    				}
    				if(count==2) {
    					flag=1;
    				}
    			}
    		}
    		printf(flag?"YES\n":"NO\n");
    	}
    	return 0;
    }