#include <bits/stdc++.h>
using namespace std;
int main() {
  int d, h, v, e;
  double S;
  double v1, v2;
  double ans;
  while (scanf("%d %d %d %d", &d, &h, &v, &e) != EOF) {
    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;
}
