#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  char mat[n][m];
  int a[m];
  string res = "NO";
  memset(a, 0, sizeof a);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      cin >> mat[i][j];
      int one = mat[i][j] - '0';
      a[j] += one;
    }
  }
  for (int i = 0; i < n; i++) {
    bool imp = false;
    for (int k = 0; k < m; k++) {
      if (mat[i][k] == '1') {
        if (a[k] == 1) {
          imp = true;
          break;
        }
      }
    }
    if (!imp) {
      res = "YES";
      break;
    }
  }
  cout << res;
  return 0;
}
