#include <bits/stdc++.h>
using namespace std;
int n, m, S[2005];
bool mark[2005][2005];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  char c;
  cin >> n >> m;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++) {
      cin >> c;
      mark[i][j] = c - '0';
      if (mark[i][j]) S[j]++;
    }
  bool flag;
  for (int i = 1; i <= n; i++) {
    flag = 0;
    for (int j = 1; j <= m; j++)
      if (mark[i][j]) S[j]--;
    for (int j = 1; j <= m; j++)
      if (S[j] == 0) {
        flag = 1;
        break;
      }
    if (!flag) {
      cout << "YES";
      return 0;
    }
    for (int j = 1; j <= m; j++)
      if (mark[i][j]) S[j]++;
  }
  cout << "NO";
  return 0;
}
