#include <bits/stdc++.h>
using namespace std;
const int dir[4][2] = {1, 0, 0, 1, -1, 0, 0, -1};
const int N = 1e6 + 10;
const int mod = 1e9 + 7;
const double pi = acos(-1);
const double eps = 1e-6;
const int INF = 0x3f3f3f3f;
template <class T>
void _print(T arg) {
  cout << arg << " ";
}
template <class... Args>
void log(Args... args) {
  int arr[] = {(_print(args), 0)...};
  cout << endl;
}
int n, m, K, r, v;
double s, f;
bool check(double x) {
  double A = cos(x / r) - 1;
  double B = sin(x / r);
  return x + r * sqrt(A * A + B * B) >= f;
}
int main() {
  ios::sync_with_stdio(0);
  cin >> n >> r >> v;
  for (int i = 1; i <= n; ++i) {
    cin >> s >> f;
    f -= s;
    double l = 0, r = 1e9;
    for (int i = 0; i < 100; i++) {
      double mid = (l + r) / 2.0;
      if (check(mid)) {
        r = mid;
      } else
        l = mid;
    }
    printf("%.7f\n", r / v);
  }
  return 0;
}
