#include <bits/stdc++.h>
using namespace std;
const int N = 2005;
char s[N][N];
int book[N];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> s[i];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (s[i][j] == '1') book[j]++;
    }
  }
  bool f = false;
  for (int i = 0; i < n; i++) {
    bool flag = true;
    for (int j = 0; j < m; j++) {
      if (s[i][j] == '1' && book[j] - 1 <= 0) {
        flag = false;
        break;
      }
    }
    if (flag) {
      f = true;
      break;
    }
  }
  if (f)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
