#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1.0);
double r, v, s, f, len;
int n;
double check(double t) {
  double s = v * t;
  double a = fmod(t * v / r, 2 * PI) / 2;
  return s + 2 * r * sin(a) >= len;
}
int main() {
  scanf("%d%lf%lf", &n, &r, &v);
  while (n--) {
    scanf("%lf%lf", &s, &f);
    len = f - s;
    double l = 0, r = len / v;
    int k = 50;
    while (k--) {
      double t = (l + r) / 2;
      if (check(t))
        r = t;
      else
        l = t;
    }
    printf("%.12lf\n", l);
  }
  return 0;
}
