#include <bits/stdc++.h>
using namespace std;
int main() {
  int(n), (r), (v);
  scanf("%d%d%d", &(n), &(r), &(v));
  ;
  for (int i = (0); i < (n); ++i) {
    int(s), (f);
    scanf("%d%d", &(s), &(f));
    ;
    double dist = (f - s) * 1.;
    double V = v * 1.;
    double R = r * 1.;
    double left = max(0., (dist - 2 * M_PI * R) / V),
           right = (dist * 1.0 + 2 * M_PI * R) / (v * 1.);
    while (right - left > 1e-7 && (right - left) / (left) > 1e-7) {
      double mid = (right + left) / 2;
      if (2 * R * abs(sin(V * mid / (2. * R))) + V * mid >= dist)
        right = mid;
      else
        left = mid;
    }
    printf("%.17lf\n", left);
  }
}
