#include <bits/stdc++.h>
using namespace std;
vector<string> switches;
vector<int> lamps;
int main(void) {
  int n, m, cnt = 0;
  scanf("%d %d", &n, &m);
  lamps.resize(m);
  for (int a = 0; a < n; a = a + 1) {
    string input;
    cin >> input;
    switches.push_back(input);
    for (int b = 0; b < m; b = b + 1) {
      lamps[b] += (switches[a][b] - '0');
    }
  }
  for (int a = 0; a < n; a = a + 1) {
    vector<int> tmp = lamps;
    for (int b = 0; b < m; b = b + 1) {
      tmp[b] = tmp[b] - (switches[a][b] - '0');
      if (tmp[b] == 0)
        break;
      else if (b == m - 1) {
        cout << "YES";
        return 0;
      }
    }
  }
  cout << "NO";
  return 0;
}
