#include <bits/stdc++.h>
using namespace std;
int main() {
  long n, m;
  cin >> n >> m;
  vector<string> s(n);
  vector<long> frag(m);
  for (long i = 0; i < n; ++i) {
    cin >> s[i];
    for (long j = 0; j < m; ++j)
      if (s[i][j] == '1') frag[j]++;
  }
  for (long i = 0; i < n; ++i) {
    bool ok = true;
    for (int j = 0; j < m; ++j)
      if (s[i][j] == '1' && frag[j] <= 1) ok = false;
    if (ok) {
      puts("YES");
      return 0;
    }
  }
  puts("NO");
  return 0;
}
