#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<string> p(n);
  for (int i = 0; i < n; i++) cin >> p[i];
  vector<int> t(m);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (p[i][j] == '1') t[j]++;
    }
  }
  for (int i = 0; i < n; i++) {
    bool f = 0, g = 0;
    ;
    for (int j = 0; j < m; j++) {
      if (t[j]) g = 1;
      if (p[i][j] == '1' && t[j] == 1) f = 1;
    }
    if (!f) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
  return 0;
}
