#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-7;
const int lim = 250;
double ans, pi, d, r0, v;
int i, j, k, n, a, b;
double solve(double x, double w) {
  double l = 0, r = (x + 4 * pi * r0) / v, m, k, cot = 0;
  while (r - l >= eps && cot <= lim) {
    m = (l + r) / 2;
    cot++;
    k = v * m + r0 * cos(w - v / r0 * m);
    if (k >= x)
      r = m;
    else
      l = m;
  }
  return r;
}
int main() {
  pi = acos(-1);
  scanf("%d%lf%lf", &n, &r0, &v);
  for (i = 1; i <= n; i++) {
    scanf("%d%d", &a, &b);
    d = (b - a) / 2.0;
    ans = min(solve(d, pi / 2), solve(d, -pi / 2));
    printf("%.9f\n", ans * 2);
  }
  return 0;
}
