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