#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m, a, b, c, t, i, j, k;
  string s;
  cin >> n >> m;
  string str[n];
  for (i = 0; i < n; i++) cin >> str[i];
  long long lamp[m + 1];
  memset(lamp, 0, sizeof lamp);
  for (i = 0; i < m; i++) {
    for (j = 0; j < n; j++) {
      lamp[i + 1] += str[j][i] - 48;
    }
  }
  for (i = 0; i < n; i++) {
    bool ok = true;
    for (j = 0; j < m; j++) {
      if (str[i][j] == '1' && lamp[j + 1] == 1) ok = false;
    }
    if (ok) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
  return 0;
}
