#include <bits/stdc++.h>
using namespace std;
int s[2000], sw[2000][2000];
int main() {
  int l, w;
  char tc;
  while (cin >> l >> w) {
    for (int i = 0; i < w; i++) s[i] = 0;
    for (int i = 0; i < l; i++) {
      getchar();
      for (int j = 0; j < w; j++) {
        tc = getchar();
        if (tc == '1') {
          s[j]++;
          sw[i][j] = 1;
        }
      }
    }
    int y = 1;
    for (int i = 0; i < l; i++) {
      y = 1;
      for (int j = 0; j < w; j++) {
        if (s[j] - sw[i][j] <= 0) {
          y = 0;
          break;
        }
      }
      if (y) break;
    }
    if (y)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  }
}
