#include <bits/stdc++.h>
int main(void) {
  int d, h, v, e;
  scanf("%d %d %d %d", &d, &h, &v, &e);
  double S = 3.141592653589 * d * d / 4;
  double V = S * h;
  double ve = e * S;
  double delta = v - ve;
  if (delta <= 0) {
    printf("NO\n");
    return 0;
  }
  double time = V / delta;
  printf("YES\n");
  printf("%.10lf\n", time);
}
