#include <bits/stdc++.h>
int main() {
  int d, h, v, e;
  double S;
  double v1, v2;
  double ans;
  scanf("%d %d %d %d", &d, &h, &v, &e);
  S = d / 2.0 * d / 2.0 * 3.14159265;
  v1 = v / S;
  v2 = e;
  ans = h / (v1 - v2);
  if (v1 <= v2 || ans - 10000 > 0.0001)
    printf("NO\n");
  else
    printf("YES\n%lf\n", ans);
  return 0;
}
