#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n;
  double r, v, si, fi;
  cin >> n >> r >> v;
  for (int i = 0; i < n; i++) {
    cin >> si >> fi;
    double dist = fi - si;
    double cir = 2 * 3.14159265358979323846 * r;
    double rev = dist / cir;
    rev = floor(rev);
    double time = rev * (cir / v);
    dist -= time * v;
    double left = 0;
    double right = cir / v;
    double x;
    while (right - left > 1e-12) {
      double mid = (left + right) / 2;
      double temp =
          2 * r * sin((mid * 3.14159265358979323846) / (cir / v)) + mid * v;
      if (temp >= dist) {
        right = mid;
      } else
        left = mid;
    }
    time += left;
    printf("%.12f\n", time);
  }
  return 0;
}
