#include <bits/stdc++.h>
using namespace std;
int main() {
  double d, h, v, e;
  scanf("%lf%lf%lf%lf", &d, &h, &v, &e);
  double S = d * d * acos(-1) / 4;
  if (S * e >= v)
    printf("NO\n");
  else {
    printf("YES\n%f\n", (S * h) / (v - S * e));
  }
  return 0;
}
