#include <bits/stdc++.h>
using namespace std;
bool b[10005];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, m;
  cin >> n >> m;
  string s[n];
  vector<int> z(m);
  for (int i = 0; i < n; i++) {
    cin >> s[i];
    for (int j = 0; j < m; j++)
      if (s[i][j] == '1') z[j]++;
  }
  for (int i = 0; i < n; i++) {
    bool hn = true;
    for (int j = 0; j < m; j++) {
      if (s[i][j] == '1' && z[j] == 1) hn = false;
    }
    if (hn == true) {
      cout << "YES" << endl;
      return 0;
    }
  }
  cout << "NO" << endl;
  return 0;
}
