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