#include <bits/stdc++.h>
using namespace std;
int N, M, i, j, nr[2005];
string s[2005];
bool ok;
int main() {
  cin >> N >> M;
  for (i = 1; i <= N; i++) {
    cin >> s[i];
    for (j = 0; j < M; j++) nr[j] += s[i][j] - '0';
  }
  for (i = 1; i <= N; i++) {
    ok = true;
    for (j = 0; j < M; j++) {
      if (s[i][j] == '1' && nr[j] == 1) {
        ok = false;
        break;
      }
    }
    if (ok == true) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
  return 0;
}
