#include <bits/stdc++.h>
using namespace std;
long long mod = 1000000007LL;
const double pi = acos(-1.0);
int main() {
  int n;
  double r, v;
  cin >> n >> r >> v;
  while (n--) {
    double s, f;
    scanf("%lf%lf", &s, &f);
    double period = (floor)((f - s) / (2.0 * pi * r));
    double d = f - s - period * 2.0 * pi * r;
    cout << setprecision(10) << fixed;
    d = d / 2.0;
    double low = 0.0;
    double high = pi / v * r;
    while (high - low > 1e-8) {
      long double mid = (low + high) / 2.0;
      long double re = v * mid + r * sin(v / r * mid);
      if (re > d)
        high = mid;
      else
        low = mid;
    }
    cout << period * 2.0 * pi * r / v + 2 * low << endl;
  }
  return 0;
}
