#include <bits/stdc++.h>
using namespace std;
const int maxn = 2007;
int n, m;
char g[maxn][maxn];
int s[maxn];
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      scanf(" %c", &g[i][j]);
      g[i][j] -= '0';
      s[j] += g[i][j];
    }
  }
  for (int i = 1; i <= n; i++) {
    bool flag = 1;
    for (int j = 1; j <= m; j++) {
      if (g[i][j] && (s[j] == 1)) flag = 0;
    }
    if (flag) return puts("YES"), 0;
  }
  puts("NO");
  return 0;
}
