#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  scanf("%d", &n), scanf("%d", &m);
  int map[n][m];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      char ch;
      scanf(" %c", &ch);
      map[i][j] = ch - '0';
    }
  }
  int lambs[m];
  for (int i = 0; i < m; i++) {
    lambs[i] = 0;
    for (int j = 0; j < n; j++) {
      lambs[i] += map[j][i];
    }
  }
  bool switches;
  for (int i = 0; i < n; i++) {
    switches = true;
    for (int j = 0; j < m; j++) {
      if (map[i][j] == 1) {
        if (lambs[j] == 1) switches = false;
      }
    }
    if (switches == true) {
      printf("YES\n");
      return 0;
      ;
    }
  }
  printf("NO\n");
}
