#include <bits/stdc++.h>
using namespace std;
const long double PI = (long double)3.1415926535897932, dwa = 2.0;
int tab[200005];
long double dist(double r, double lo) {
  long double cC, pom = dwa * r;
  long double cU = modf(lo, &cC);
  cC = lo * pom * PI;
  cU *= PI;
  cU = sin(cU) * pom;
  return cU + cC;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  long long n, rr, vv;
  cin >> n >> rr >> vv;
  double r = rr, v = vv;
  double pocz, kon;
  cout << setprecision(7) << fixed;
  while (n--) {
    double a, b;
    cin >> a >> b;
    b -= a;
    double p = 0, k = 200000000, s;
    for (int i = 0; i < 80; i++) {
      s = (p + k) / (long double)dwa;
      double pom = dist(r, s);
      if (pom > b)
        k = s;
      else {
        p = s;
      }
    }
    cout << dwa * PI * r * p / v << "\n";
  }
  return 0;
}
