#include <bits/stdc++.h>
using namespace std;
int b[2001];
vector<int> v;
int a[2003][2004];
int main() {
  ios_base::sync_with_stdio(false);
  long long n, t, m;
  string s[2000];
  cin >> n >> m;
  for (int i = 0; i < n; ++i) {
    cin >> s[i];
  }
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      a[i][j] = s[i][j];
    }
  }
  int c = 0, in = 0;
  for (int i = 0; i < m; ++i) {
    c = 0;
    for (int j = 0; j < n; ++j) {
      if (a[j][i] == '1') {
        c++;
        in = j;
      }
    }
    if (c == 1) {
      b[in] = 1;
    }
  }
  for (int i = 0; i < n; ++i) {
    if (b[i] == 0) {
      cout << "YES" << endl;
      return 0;
    }
  }
  cout << "NO" << endl;
  return 0;
}
