#include <bits/stdc++.h>
using namespace std;
int main() {
  int d, h, v, e, j;
  scanf("%d%d%d%d", &d, &h, &v, &e);
  double r = (d / 2.0);
  double a = (M_PI)*r * r;
  double dd = a * e;
  if (dd >= v) {
    printf("NO");
  } else {
    double i = a * h;
    double t = (i * 1.0) / (v - dd);
    printf("YES\n");
    printf("%lf\n", t);
  }
  return 0;
}
