#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, r, v;
  cin >> n >> r >> v;
  for (int i = 1; i <= n; i++) {
    double s, f;
    scanf("%lf%lf", &s, &f);
    f -= s;
    double st = 0, ed = f / r;
    for (int j = 1; j <= 50; j++) {
      double mid = (st + ed) / 2;
      if (1.0 * r * (mid + 2 * fabs(sin(mid / 2))) > f)
        ed = mid;
      else
        st = mid;
    }
    double L = st * r;
    L /= v;
    printf("%.10lf\n", L);
  }
  return 0;
}
