#include <bits/stdc++.h>
using namespace std;
int n;
double r, v;
const double pi = 4. * atan2(1., 1.);
const double eps = 1e-8;
double search(double a) {
  double l = 0, R = pi * 2. * r / v, mid;
  while (fabs(l - R) > eps) {
    mid = (l + R) / 2;
    if ((mid * v + 2 * r * sin(v * mid / 2. / r)) > a)
      R = mid;
    else
      l = mid;
  }
  return l;
}
int main() {
  scanf("%d", &n);
  scanf("%lf%lf", &r, &v);
  double rou = r * pi * 2.;
  for (int i = 1; i <= n; ++i) {
    double s, t;
    scanf("%lf%lf", &s, &t);
    double len = t - s;
    double l = rou * (int)(len / rou);
    len -= l;
    printf("%lf\n", l / v + search(len));
  }
  return 0;
}
