#include <bits/stdc++.h>
const long double PI = 3.14159265359;
using namespace std;
int n;
long double r, v;
long double dis;
int check(long double t) {
  if (t <= 0) return 0;
  long double tmp = floor(t / (2 * PI * r));
  tmp *= 2 * PI * r;
  long double hlp = t - tmp;
  hlp /= 2 * r;
  hlp = r * sin(hlp);
  hlp *= 2;
  if (t + hlp >= dis) return 1;
  return 0;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> r >> v;
  cout << setprecision(15);
  for (int i = 0; i < n; i++) {
    long double s, f;
    cin >> s >> f;
    dis = f - s;
    long double yla = dis;
    long double ala = dis - 2 * r;
    for (int j = 0; j < 50; j++) {
      long double mid = (ala + yla) / 2;
      if (check(mid))
        yla = mid;
      else
        ala = mid;
    }
    cout << ala / v << "\n";
  }
}
