#include <bits/stdc++.h>
using namespace std;
char s[2200][2200];
int a[2020];
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%s", s[i]);
  memset(a, 0, sizeof(a));
  for (int i = 0; i < m; i++) {
    for (int j = 0; j < n; j++) {
      if (s[j][i] == '1') a[i]++;
    }
  }
  int flag = 0;
  for (int i = 0; i < n; i++) {
    int f = 1;
    for (int j = 0; j < m; j++) {
      if (a[j] - (s[i][j] - '0') <= 0) f = 0;
    }
    if (f == 1) {
      flag = 1;
      break;
    }
  }
  if (flag)
    printf("YES\n");
  else
    printf("NO\n");
  return 0;
}
