#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, m;
  cin >> n >> m;
  vector<string> v;
  string s;
  int cnt[m];
  memset(cnt, 0, sizeof cnt);
  for (int i = 0; i < n; i++) {
    cin >> s;
    for (int j = 0; j < m; j++) {
      if (s[j] == '1') cnt[j]++;
    }
    v.push_back(s);
  }
  for (int i = 0; i < n; i++) {
    s = v[i];
    bool f = true;
    for (int j = 0; j < m; j++) {
      if (s[j] == '1' && cnt[j] == 1) {
        f = false;
        break;
      }
    }
    if (f == true) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
  return 0;
}
