#include <bits/stdc++.h>
using namespace std;
const double PI =
    3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679;
double r, v, w;
double s;
int Moze(double t) {
  double pozdol = v * t;
  double alfa2 = PI + w * t / 2;
  double alfa1 = 2 * PI - alfa2;
  return pozdol + 2 * r * abs(sin(alfa1)) > s;
}
int main() {
  int q;
  scanf("%d%lf%lf", &q, &r, &v);
  w = v / r;
  for (; q; q--) {
    int poc, kraj;
    scanf("%d%d", &poc, &kraj);
    s = kraj - poc;
    double lo = 0, hi = 1e10;
    for (int i = 0; i < 100; i++) {
      double mid = (lo + hi) / 2;
      if (Moze(mid))
        hi = mid;
      else
        lo = mid;
    }
    printf("%.10lf\n", lo);
  }
  return 0;
}
