#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  string arr[n];
  int count[m];
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
  }
  for (int i = 0; i < m; i++) {
    count[i] = 0;
    for (int j = 0; j < n; j++) {
      count[i] += arr[j][i] - '0';
    }
  }
  for (int i = 0; i < n; i++) {
    bool found = true;
    for (int j = 0; j < m; j++) {
      if (arr[i][j] == '1' && count[j] == 1) {
        found = false;
        break;
      }
    }
    if (found == true) {
      cout << "YES" << endl;
      goto l;
    }
  }
  cout << "NO" << endl;
l:;
  return 0;
}
