#include <bits/stdc++.h>
using namespace std;
char arr[2009][2009];
int nums[2009][2009], n, m, s[2009], temp[2009], cnt, ans;
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; ++i)
    for (int j = 0; j < m; ++j) cin >> arr[i][j];
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      if (arr[i][j] == '1')
        nums[i][j] = 1;
      else
        nums[i][j] = 0;
    }
  }
  for (int i = 0; i < m; ++i) {
    int sum = 0;
    for (int j = 0; j < n; ++j) {
      sum += nums[j][i];
    }
    s[cnt++] = sum;
  }
  for (int j = 0; j < m; ++j) temp[j] = s[j];
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      temp[j] -= nums[i][j];
    }
    bool f = 1;
    for (int k = 0; k < m; ++k) {
      if (temp[k] == 0) f = 0;
    }
    if (f) {
      cout << "YES";
      return 0;
    }
    for (int l = 0; l < m; ++l) temp[l] = s[l];
  }
  cout << "NO";
  return 0;
}
