#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1.0);
int n, r, v;
int main() {
  scanf("%d%d%d", &n, &r, &v);
  for (int i = 1; i <= n; i++) {
    int l0, r0;
    scanf("%d %d", &l0, &r0);
    double dist = r0 - l0;
    double cir = 2.0 * PI * r;
    double cnt = floor(dist / cir);
    double left = dist - cnt * cir;
    double L = 0, R = left / 2;
    for (int j = 0; j < 100; j++) {
      double m = (L + R) / 2;
      double now = r * sin(m / r) + m;
      if (now < left * 0.5)
        L = m;
      else
        R = m;
    }
    double ans = L * 2 + cnt * cir;
    printf("%.10f\n", ans / v);
  }
}
