#include <bits/stdc++.h>
int n;
double r, v;
double dist;
double mabs(double x) {
  if (x > 0) return x;
  return -x;
}
int para(double x) {
  double t = x + r * mabs(2 * sin(x / r / 2));
  if (t > dist) return 1;
  return 0;
}
int main() {
  int i, j;
  double a, b;
  scanf("%d%lf%lf", &n, &r, &v);
  for (i = 0; i < n; i++) {
    scanf("%lf%lf", &a, &b);
    dist = b - a;
    a = 0;
    b = 1e20;
    for (j = 0; j < 100; j++) {
      if (para(a + b) == 0) a += b;
      b /= 2;
    }
    printf("%.20lf\n", a / v);
  }
}
