#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
int n;
double r, v, l;
double tim(double p1, double p2) {
  double rem = p2 - p1;
  double k = int(rem / l);
  rem = rem - k * l;
  double le = 0, ri = 1e9, mid;
  for (int I = 1; I <= 200; I++) {
    mid = (le + ri) / 2.0;
    if (v * mid + 2 * sin(v * mid / (2 * r)) * r >= rem) {
      ri = mid;
    } else {
      le = mid;
    }
  }
  return mid + double(k * l) / v;
}
int main() {
  scanf("%d%lf%lf", &n, &r, &v);
  l = 3.141592653589 * r * 2;
  for (int i = 1; i <= n; i++) {
    int p1, p2;
    scanf("%d%d", &p1, &p2);
    printf("%.10f\n", float(tim(double(p1), double(p2))));
  }
  return 0;
}
