#include <bits/stdc++.h>
using namespace std;
int a[2005][2005], b[2005];
int main() {
  int n, m;
  char item;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    getchar();
    for (int j = 1; j <= m; j++) {
      cin >> item;
      a[i][j] = item - '0';
    }
  }
  for (int j = 1; j <= m; j++) {
    for (int i = 1; i <= n; i++) {
      if (a[i][j] == 1) b[j]++;
    }
  }
  for (int i = 1; i <= n; i++) {
    int sign = 0;
    for (int j = 1; j <= m; j++) {
      if (a[i][j] == 1 && b[j] == 1) {
        sign = 1;
        break;
      }
    }
    if (sign == 0) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
  return 0;
}
