#include <bits/stdc++.h>
using namespace std;
const int M = 3e3;
int n, m;
string a[M];
int counter[M];
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (a[i][j] == '1') {
        counter[j]++;
      }
    }
  }
  for (int i = 0; i < n; i++) {
    bool good = true;
    for (int j = 0; j < m; j++) {
      if (a[i][j] == '1' && counter[j] == 1) {
        good = false;
      }
    }
    if (good) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
}
