#include <bits/stdc++.h>
using namespace std;
double r, v;
double a, b;
bool check(double l) {
  double arfa = l / r;
  double A = r * (1 - cos(arfa));
  double B = r * sin(arfa);
  return l + sqrt(A * A + B * B) >= b - a;
}
int main(void) {
  int n;
  cin >> n >> r >> v;
  for (int i = 1; i <= n; i++) {
    scanf("%lf%lf", &a, &b);
    double l = 0, r = b - a, ans;
    for (int i = 1; i <= 50; i++) {
      double mid = (l + r) / 2.0;
      if (check(mid))
        ans = mid, r = mid;
      else
        l = mid;
    }
    printf("%.10f\n", ans / v);
  }
  return 0;
}
