#include <bits/stdc++.h>
using namespace std;
string ss[2005];
int sums[2005];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  for (int x = 0; x < n; x++) {
    cin >> ss[x];
    for (int i = 0; i < m; i++) {
      if (ss[x][i] == '1') {
        sums[i]++;
      }
    }
  }
  bool broke;
  for (int x = 0; x < n; x++) {
    broke = false;
    for (int i = 0; i < m; i++) {
      if (ss[x][i] == '1' && sums[i] == 1) {
        broke = true;
        break;
      }
    }
    if (broke == false) {
      cout << "YES\n";
      return 0;
    }
  }
  cout << "NO\n";
  return 0;
  return 0;
}
