#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  std::cin >> n >> m;
  getchar();
  int a[n][m], nums[m];
  for (int i = 0; i < m; i++) {
    nums[i] = 0;
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      a[i][j] = getchar() - '0';
      nums[j] += a[i][j];
    }
    getchar();
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (a[i][j]) {
        if (nums[j] == 1) goto A;
      }
    }
    std::cout << "YES";
    return 0;
  A:;
  }
  printf("NO");
  return 0;
}
