#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1);
int main() {
  int n;
  double s, a, x, l, h, r, v, st, ed;
  scanf("%d%lf%lf", &n, &r, &v);
  for (int i = 0; i < n; ++i) {
    scanf("%lf%lf", &st, &ed);
    h = ed - st, l = 0;
    while (h - l > 1e-6) {
      s = 0.5 * (h + l);
      ;
      a = fmod(s / (2 * r), pi);
      if (ed - st - s > 2 * r * sin(a))
        l = s;
      else
        h = s;
    }
    printf("%.8f\n", double(s / v));
  }
  return 0;
}
