#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<vector<int>> a(n, vector<int>(m, 0));
  for (int i = 0; i < n; ++i) {
    string s;
    cin >> s;
    for (int j = 0; j < m; ++j) {
      a[i][j] = s[j] - '0';
    }
  }
  vector<int> b(n, 0);
  for (int j = 0; j < m; ++j) {
    int flag = 0;
    int num;
    for (int i = 0; i < n; ++i) {
      if (a[i][j] == 1) {
        num = i;
        ++flag;
      }
    }
    if (flag == 1) {
      b[num] = 1;
    }
  }
  for (auto it : b) {
    if (!it) {
      cout << "YES\n";
      return 0;
    }
  }
  cout << "NO\n";
}
