#include <bits/stdc++.h>
using namespace std;
const int N = 2020;
int n, m, i, j, cnt[N];
char grid[N][N];
bool check(int s) {
  for (int i = 0; i < m; ++i)
    if (grid[s][i] == '1' && cnt[i] <= 1) return 0;
  return 1;
}
int main() {
  cin >> n >> m;
  for (i = 0; i < n; ++i) {
    scanf("%s", grid + i);
    for (j = 0; j < m; ++j) {
      cnt[j] += (grid[i][j] == '1');
    }
  }
  for (i = 0; i < n; ++i) {
    if (check(i)) {
      return cout << "YES", 0;
    }
  }
  cout << "NO";
  return 0;
}
