#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
int mcm(int a, int b) { return a * b / gcd(a, b); }
int sq(int a) { return a * a; }
int pot(int a, int b) { return b ? sq(pot(a, b >> 1)) * (b & 1 ? a : 1) : 1; }
int main() {
  int n, r, v;
  cin >> n >> r >> v;
  double ciclo = 2 * 3.14159265358979323846264338327950288 * (double)r;
  double T = ciclo / v;
  double circum = 2 * 3.14159265358979323846264338327950288 * (double)r;
  double Time = circum / v;
  for (int i = (0); i < n; i++) {
    int s, f;
    cin >> s >> f;
    double tam = f - s;
    double nVueltas = floor(tam / ciclo);
    tam -= nVueltas * ciclo;
    double res = T * nVueltas;
    double L = 0, R = T;
    double q;
    while (R - L > 1e-9) {
      double mid = (L + R) / 2;
      double z =
          2 * r * sin((mid * 3.14159265358979323846264338327950288) / T) +
          mid * v;
      if (z >= tam) {
        q = mid;
        R = mid;
      } else {
        L = mid;
      }
    }
    res += q;
    printf("%.12lf\n", res);
  }
}
