#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n, m;
  cin >> n >> m;
  vector<vector<long long> > vec(n, vector<long long>(m));
  vector<long long> data(m, 0);
  for (long long i = 0; i < n; i++)
    for (long long j = 0; j < m; j++) {
      char c;
      cin >> c;
      vec[i][j] = c - '0';
      if (vec[i][j]) data[j]++;
    }
  for (long long i = 0; i < n; i++) {
    vector<long long> data1 = data;
    for (long long j = 0; j < m; j++)
      if (vec[i][j]) data1[j]--;
    bool ok = true;
    for (long long j = 0; j < m; j++)
      if (data1[j] <= 0) ok = false;
    if (ok) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
  return 0;
}
