#include <bits/stdc++.h>
using namespace std;
int main() {
  int d, h, v, e;
  scanf("%d%d%d%d", &d, &h, &v, &e);
  double s = (d * 1.0 / 2) * (d * 1.0 / 2) * 3.1415926;
  double ch = v * 1.0 / s * 1.0;
  if (ch <= e)
    printf("NO\n");
  else
    printf("YES\n%lf\n", h * 1.0 / (ch - e) * 1.0);
}
