#include <bits/stdc++.h>
using namespace std;
int n, m, f[2001] = {0};
bool p, a[2001][2001];
string st;
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    cin >> st;
    for (int j = 0; j < m; j++)
      if (st[j] == '1') {
        a[i][j + 1] = true;
        f[j + 1]++;
      } else
        a[i][j + 1] = false;
  }
  for (int i = 1; i <= n; i++) {
    p = true;
    for (int j = 1; j <= m; j++)
      if (f[j] == 1 && a[i][j] == 1) p = false;
    if (p) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
}
