#include <bits/stdc++.h>
using namespace std;
double revs, a, b, c, d, C, totdist;
const double pi = atan(1) * 4;
int n, r, v, s, f;
double distcovered(double t) { return max(r * (t + sin(t)), r * (t - sin(t))); }
int main() {
  cout << fixed << setprecision(8);
  cin >> n >> r >> v;
  for (int c = 0; c < n; c++) {
    scanf("%d%d", &s, &f);
    a = f - s;
    a = a / 2;
    double up, low;
    low = 0;
    up = a / r + 2 * pi;
    for (int c = 0; c < 200; c++) {
      double mid = (low + up) / 2;
      b = distcovered(mid);
      if (b == a)
        break;
      else if (b > a)
        up = mid;
      else
        low = mid;
    }
    double mid = (low + up) / 2;
    double speed = (double)v / r;
    double time = mid / speed * 2;
    printf("%.8f\n", time);
  }
  return 0;
}
