#include <bits/stdc++.h>
using namespace std;
const double PI = 2 * acos(0.0);
int n, r, v, s, f;
int main() {
  scanf("%d%d%d", &n, &r, &v);
  for (int i = 0; i < n; i++) {
    scanf("%d%d", &s, &f);
    double x = f - s;
    double low1 = 0, low2 = 0;
    double high1 = 2e9, high2 = 2e9;
    for (int rep = 0; rep < 60; rep++) {
      double mid = (low1 + high1) / 2;
      double ang = v * mid / r;
      if (r * (ang - sin(ang)) > x / 2)
        high1 = mid;
      else
        low1 = mid;
      mid = (low2 + high2) / 2;
      ang = v * mid / r + PI;
      if (r * (ang - sin(ang) - PI) > x / 2)
        high2 = mid;
      else
        low2 = mid;
    }
    printf("%1.9f\n", min(high1, high2) * 2);
  }
  return 0;
}
