Codeforces 691A Fashion in Berland

水题。

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi = acos(-1.0), eps = 1e-8;
void File()
{
    freopen("D:\in.txt", "r", stdin);
    freopen("D:\out.txt", "w", stdout);
}
inline int read()
{
    char c = getchar();  while (!isdigit(c)) c = getchar();
    int x = 0;
    while (isdigit(c)) { x = x * 10 + c - '0'; c = getchar(); }
    return x;
}

int n,a[1010],sz;

int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++) {scanf("%d",&a[i]); if(a[i]==1) sz++;}
    if(n==1)
    {
        if(a[1]==1) printf("YES
");
        else printf("NO
");
    }
    else
    {
        if(sz!=n-1) printf("NO
");
        else printf("YES
");
    }

    return 0;
}