#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2010;
int N, M;
char A[MAXN][MAXN];
int cnt[MAXN];
int main() {
  scanf("%d %d", &N, &M);
  for (int i = 0; i < N; i++) {
    scanf("%s", A[i]);
    for (int j = 0; j < M; j++) {
      if (A[i][j] == '1') {
        cnt[j]++;
      }
    }
  }
  for (int i = 0; i < N; i++) {
    bool need = false;
    for (int j = 0; j < M; j++) {
      if (A[i][j] == '1' && cnt[j] == 1) {
        need = true;
        break;
      }
    }
    if (!need) {
      puts("YES");
      return 0;
    }
  }
  puts("NO");
}
