#include <bits/stdc++.h>
using namespace std;
const int INF = 0x7f7f7f7f;
const int MOD = 1e9 + 7;
const double eps = 1e-6;
int main() {
  int n, r, v;
  scanf("%d%d%d", &n, &r, &v);
  double s = acos(-1.0) * r * 2;
  while (n--) {
    int a, b;
    scanf("%d%d", &a, &b);
    double d = b - a;
    int c = (d / s);
    double len = d - c * s;
    double L = 0, R = len;
    double mid = (L + R) / 2;
    while (R - L >= eps) {
      if (mid + 2 * r * sin(mid / 2 / r) >= len)
        R = mid;
      else
        L = mid;
      mid = (L + R) / 2;
    }
    printf("%.12lf\n", (c * s + mid) / v);
  }
  return 0;
}
