#include <bits/stdc++.h>
const long double pi = acos(-1);
const long double eps = 1e-18;
long double k2, t, z, ll, rr, mid;
double r, v, x, y;
int i, n;
int main() {
  scanf("%d%lf%lf", &n, &r, &v);
  for (i = 1; i <= n; i++) {
    scanf("%lf%lf", &x, &y);
    z = y - x;
    k2 = trunc(z / pi / r / 2);
    ll = 0, rr = pi;
    while (rr - ll > eps) {
      mid = (ll + rr) / 2;
      if (2 * mid * r + 2 * k2 * r * pi + sin(mid) * 2 * r < z)
        ll = mid;
      else
        rr = mid;
    }
    printf("%.10lf\n", (double)((2 * ll * r + 2 * k2 * r * pi) / v));
  }
  return 0;
}
