k experienced teams are participating in the contest. Some of these teams already know some of the problems. To make the contest interesting for them, each of the teams should know at most half of the selected problems.

Determine if Snark and Philip can make an interesting problemset!

The first line contains two integers n, k (1?≤?n?≤?10⁵, 1?≤?k?≤?4) — the number of problems and the number of experienced teams.

Each of the next n lines contains k integers, each equal to 0 or 1. The j-th number in the i-th line is 1 if j

Print "YES" (quotes for clarity), if it is possible to make an interesting problemset, and "NO" otherwise.

You can print each character either upper- or lowercase ("YeS" and "yes" are valid when the answer is "YES").

5 3
1 0 1
1 1 0
1 0 0
1 0 0
1 0 0

NO

3 2
1 0
1 1
0 1

YES
在 n 道題目中挑選一些使得所有人對題目的掌握情況不超過一半。

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
bool vis[22];
int main(){
    int n,k,x;
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;++i) {
    int sum=0;
    for(int j=1;j<=k;++j) {
        scanf("%d",&x);
        if(x) sum+=1<<(j-1);
    }
    vis[sum]=1;
    }
    bool flag=0;
    for(int i=0;i<=15;++i) for(int j=0;j<=15;++j) if(((i&j)==0)&&vis[i]&&vis[j]) flag=1; 
    if(flag) puts("YES");else puts("NO");
}

在 n 道題目中挑選一些使得所有人對題目的掌握情況不超過一半。