#include <bits/stdc++.h>
using namespace std;
const double error = 1e-7;
double v, r;
bool puede(double t, double dist) {
  dist -= v * t;
  if (dist <= 0) return true;
  double tvuelta = r * 2 * M_PI / v;
  t -= int(t / tvuelta) * tvuelta;
  double a = t * v / r;
  return dist <= 2 * r * sin(a / 2.0);
}
int main() {
  cout.setf(ios::fixed);
  cout.precision(10);
  int n;
  cin >> n >> r >> v;
  for (int cas = 0; cas < n; cas++) {
    int s, f;
    cin >> s >> f;
    double inf = 0;
    double sup = 2000000000;
    double d = f - s;
    while (inf + error < sup) {
      double med = (inf + sup) / 2.0;
      if (puede(med, d))
        sup = med;
      else
        inf = med;
    }
    cout << inf << endl;
  }
}
