#include <bits/stdc++.h>
using namespace std;
const int N = 2100;
const long long inf = 1e9;
int a[N];
string s[N];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < n; ++i) {
    cin >> s[i];
    for (int j = 0; j < m; ++j) {
      if (s[i][j] == '1') a[j]++;
    }
  }
  for (int i = 0; i < n; ++i) {
    int mark = 0;
    for (int j = 0; j < m; ++j) {
      if (s[i][j] == '1' && a[j] == 1) mark = 1;
    }
    if (!mark) {
      cout << "YES\n";
      return 0;
    }
  }
  cout << "NO\n";
  return 0;
}
