#include <bits/stdc++.h>
const int INF = 0x7F7F7F7F;
const double EPS = 1e-10;
const long long mod7 = 1e9 + 7;
const long long mod9 = 1e9 + 9;
using namespace std;
inline long long rit() {
  long long f = 0, key = 1;
  char c;
  do {
    c = getchar();
    if (c == '-') key = -1;
  } while (c < '0' || c > '9');
  do {
    f = f * 10 + c - '0';
    c = getchar();
  } while (c >= '0' && c <= '9');
  return f * key;
}
inline void fprt(double f) { printf("%.08lf", f); }
const double MPI = acos(-1.0);
void init() {}
double d, h, v, e;
void read() {
  d = rit(), h = rit();
  ;
  v = rit(), e = rit();
  ;
}
void solve() {
  double m;
  m = (d / 2) * (d / 2) * MPI;
  v /= m;
  if (v <= e) {
    cout << "NO" << endl;
    return;
  } else {
    cout << "YES" << endl;
    cout << h / (v - e) << endl;
  }
}
int main() {
  int nn = 1;
  init();
  while (nn--) {
    read();
    solve();
  }
  return 0;
}
