#include <bits/stdc++.h>
const int INF = 1e9;
const long long lINF = 1e18;
const double EPS = 1e-12;
using namespace std;
const int maxn = 5e5 + 100;
const double PI = acos(-1);
int n;
double r, v;
int main() {
  scanf("%d%lf%lf", &n, &r, &v);
  for (int i = 0; i < n; i++) {
    double s, f;
    scanf("%lf%lf", &s, &f);
    double dist = f - s;
    double ans = floor(dist / 2 / PI / r) * 2 * PI * r / v;
    dist -= floor(dist / 2 / PI / r) * 2 * PI * r;
    double L = 0, R = PI;
    for (int t = 0; t < 100; t++) {
      double mid = (L + R) / 2;
      if ((mid + sin(mid)) * r > dist / 2) {
        R = mid;
      } else {
        L = mid;
      }
    }
    ans += r / v * L * 2;
    printf("%.18f\n", ans);
  }
  return 0;
}
