#include <bits/stdc++.h>
using namespace std;
int a[2000][2000];
int sum[2000];
int main() {
  int n, m;
  cin >> n >> m;
  char ch;
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      cin >> ch;
      if (ch == 'n') {
        break;
      } else {
        a[i][j] = ch - '0';
        if (a[i][j] == 1) {
          sum[j] += 1;
        }
      }
    }
  }
  if (*min_element(sum, sum + m) >= 2) {
    cout << "YES\n";
    return 0;
  }
  int temp[m];
  bool failflag = false;
  for (int i = 0; i < n; ++i) {
    failflag = false;
    for (int j = 0; j < m; ++j) {
      temp[j] = sum[j] - a[i][j];
      if (temp[j] == 0) {
        failflag = true;
        break;
      }
    }
    if (!failflag) {
      cout << "YES\n";
      return 0;
    }
  }
  cout << "NO\n";
}
