#include <bits/stdc++.h>
using namespace std;
int t, n;
double v, r, pi = acos(-1), s, f, eps = 1e-9;
int work(double p) {
  double len = p * v / r / 2;
  len = 2 * r * fabs(sin((len)));
  return p * v + len >= f - s - eps;
}
int main() {
  cin >> n >> r >> v;
  while (n--) {
    scanf("%lf%lf", &s, &f);
    double low = 0, high = 2 * f, mid;
    while ((high - low) / low > eps) {
      mid = (low + high) / 2;
      if (work(mid))
        high = mid;
      else
        low = mid;
    }
    printf("%.8f\n", low);
  }
}
