Codeforces_714_B

http://codeforces.com/problemset/problem/714/B

当不同大小整数有1、2个时，肯定成立，3个时，需要判断，大于等于4个，则肯定不成立。

#include <algorithm>
#include <iostream>
#include <cstdio>
using namespace std;

long long a [];
int main()
{
    int n;
    cin >> n;
    int num = ;
    while(n--)
    {
        if(num > )
        {
            break;
        }
        long long temp;
        cin >> temp;
        int flag = ;
        for(int i = ;i < num;i++)
        {
            if(a[i] == temp)    flag = ;
        }
        if(flag) a[num++] = temp;
    }
    if(num ==  || num == )    printf("YES\n");
    else if(num == )
    {
        sort(a,a+);
        if(a[]+a[] == *a[]) printf("YES\n");
        else    printf("NO\n");
    }
    else
    {
        printf("NO\n");
    }

    return ;
}