#include <bits/stdc++.h>
using namespace std;
const long long inf = 1e11;
const long long N = 2020;
long long a[N][N], n, m, cnt[N] = {0};
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n >> m;
  for (long long i = 0; i < (n); ++i) {
    for (long long j = 0; j < (m); ++j) {
      char c;
      cin >> c;
      a[i][j] = c - '0';
      cnt[j] += a[i][j];
    }
  }
  long long f = 0;
  for (long long i = 0; i < (n); ++i) {
    long long k = 0;
    for (long long j = 0; j < (m); ++j) {
      if (a[i][j] == 1 && cnt[j] == 1) {
        k = 1;
        break;
      }
    }
    if (k == 0) {
      f = 1;
      break;
    }
  }
  if (f)
    cout << "YES";
  else
    cout << "NO";
}
