#include <bits/stdc++.h>
const double pi = acos(-1.0);
int main() {
  int d, h, v, e;
  double h2;
  scanf("%d%d%d%d", &d, &h, &v, &e);
  h2 = (double)v / (pi * pow((double)d / 2, 2));
  if (h2 <= e)
    printf("NO");
  else {
    printf("YES\n");
    printf("%.15lf", (double)h / (h2 - e));
  }
  return 0;
}
