#include <bits/stdc++.h>
using namespace std;
int n;
double r, v;
double s, f;
bool C(double x) {
  double dist = x * v;
  double am = fmod(dist / 2.0, 2.0 * r * M_PI);
  double dir = am / r;
  double cen = sin(dir);
  return dist + fabs(cen) * r * 2.0 >= f - s;
}
int main(void) {
  scanf("%d %lf %lf", &n, &r, &v);
  for (int i = 0; i < n; i++) {
    scanf("%lf %lf", &s, &f);
    double l = 0.0, r = 1e10;
    for (int i = 0; i < 100; i++) {
      double mid = (l + r) / 2.0;
      if (C(mid))
        r = mid;
      else
        l = mid;
    }
    printf("%.15f\n", r);
  }
  return 0;
}
