#include <bits/stdc++.h>
using namespace std;
int n;
double r, v, a, b, ans;
inline bool check(double x) {
  double tmp = x / r;
  double A = r * (1 - cos(tmp));
  double B = r * sin(tmp);
  return x + sqrt(A * A + B * B) >= b - a;
}
int main() {
  scanf("%d%lf%lf", &n, &r, &v);
  for (int i = 1; i <= n; i++) {
    scanf("%lf%lf", &a, &b);
    double ll = 0, rr = b - a;
    int clk = 0;
    while (ll + 1e-10 < rr) {
      double mid = (ll + rr) / 2.0;
      if (check(mid))
        ans = rr = mid;
      else
        ll = mid;
      clk++;
      if (clk > 50) break;
    }
    printf("%.10lf\n", ans / v);
  }
  return 0;
}
