#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, y, z, a, b, c;
  cin >> x >> y >> z;
  cin >> a >> b >> c;
  if (x > a || y > a - x + b || z > a + b + c - x - y)
    cout << "NO";
  else
    cout << "YES";
  return 0;
}
