#include <bits/stdc++.h>   using namespace std;   const int N = 2020;   int n, m, i, j, cnt[N];   char grid[N][N];   bool check(int s) {     for (int i = 0; i < m; ++i)       if (grid[s][i] ==  1  && cnt[i] <= 1) return 0;     return 1;   }   int main() {     cin >> n >> m;     for (i = 0; i < n; ++i) {       scanf( %s , grid + i);       for (j = 0; j < m; ++j) {         cnt[j] += (grid[i][j] ==  1 );       }     }     for (i = 0; i < n; ++i) {       if (check(i)) {         return cout <<  YES , 0;       }     }     cout <<  NO ;     return 0;   }   