#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  double r, v;
  cin >> n >> r >> v;
  double w = v / r;
  while (n--) {
    double s, e;
    scanf("%lf %lf", &s, &e);
    double d = e - s;
    double lo = 0.0, hi = 1e9;
    for (int it = 1; it <= 100; it++) {
      double mid = (lo + hi) / 2.0;
      double x = v * mid + 2.0 * r * abs(sin((w * mid) / 2.0));
      if (x >= d) {
        hi = mid;
      } else {
        lo = mid;
      }
    }
    printf("%.12f\n", lo);
  }
}
