#include <bits/stdc++.h>
int main() {
  float d, h, v, e, t, ha;
  scanf("%f %f %f %f", &d, &h, &v, &e);
  ha = v / (pow((d / 2.0), 2) * 3.1415926535897);
  if (ha <= e) {
    printf("NO\n");
  } else {
    printf("YES\n");
    t = (1 / (ha - e)) * h;
    printf("%.12f", t);
  }
}
