#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-7;
double cal1(double d, double r) { return d + r * sin(d / r); }
double cal2(double d, double r) { return d - r * sin(d / r); }
int main() {
  int t;
  double r, v;
  cin >> t >> r >> v;
  while (t--) {
    double ans;
    int x, y;
    cin >> x >> y;
    double l = y - x;
    l /= 2.0;
    double ll = 0.0, rr = l;
    while (ll + eps < rr) {
      double mid = (ll + rr) / 2.0;
      if (cal1(mid, r) < l)
        ll = mid;
      else
        rr = mid;
    }
    ans = ll;
    ll = 0.0, rr = l;
    while (ll + eps < rr) {
      double mid = (ll + rr) / 2.0;
      if (cal2(mid, r) < l)
        ll = mid;
      else
        rr = mid;
    }
    ans = min(ans, ll);
    printf("%.8lf\n", ans * 2 / v);
  }
  return 0;
}
