#include <bits/stdc++.h>
using namespace std;
int p[2005] = {0};
int main() {
  int n, m, i, j, k;
  scanf("%d%d", &n, &m);
  string s[n];
  for (i = 0; i < n; i++) {
    cin >> s[i];
    for (j = 0; j < s[i].size(); j++) {
      p[j] += s[i][j] - '0';
    }
  }
  int fag = 0;
  for (i = 0; i < n; i++) {
    int fag1 = 0;
    for (j = 0; j < m; j++) {
      if (s[i][j] == '1') p[j]--;
      if (p[j] == 0) fag1 = 1;
    }
    if (fag1 == 0) {
      fag = 1;
    }
    for (j = 0; j < m; j++) {
      if (s[i][j] == '1') p[j]++;
    }
  }
  if (fag == 1)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
