#include <bits/stdc++.h>
using namespace std;
long long a[2003][2003];
long long cnt[2003];
int main() {
  ios_base::sync_with_stdio(0);
  int n, m;
  string s;
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    cin >> s;
    for (int j = 0; j < s.size(); j++) a[i][j] = s[j] - '0', cnt[j] += a[i][j];
  }
  for (int i = 0; i < n; i++) {
    int f = 0;
    for (int j = 0; j < m; j++) {
      if (a[i][j] == 1 && cnt[j] == 1) {
        f = 1;
        break;
      }
    }
    if (!f) {
      cout << "YES" << endl;
      return 0;
    }
  }
  cout << "NO" << endl;
  return 0;
}
