#include <bits/stdc++.h>
using namespace std;
int main() {
  double d, h, v, e;
  cin >> d >> h >> v >> e;
  double s = 3.141592653589793 * (d * d) / 4;
  double u = e * s;
  if (u >= v) {
    printf("NO\n");
  } else {
    double ans = h * s / (v - u);
    printf("YES\n%.10f", ans);
  }
  return 0;
}
