#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const double eps = 1e-8;
const int T = 23;
inline double sqr(double x) { return x * x; }
inline int dcmp(double x) { return fabs(x) <= eps ? 0 : (x > 0 ? 1 : -1); }
int n;
double r, v, s, t;
bool check(double x) {
  double len = x;
  int tmp = (int)(x / (2.0 * pi * r));
  x -= 2.0 * pi * r * tmp;
  double delta = x / r;
  len -= (t - s);
  len /= r;
  double y = sqrt(sqr(1 - cos(delta)) + sqr(sin(delta)));
  len /= y;
  double a = acos(len) - acos((1 - cos(delta)) / y);
  if (a - 2.0 * pi >= 0) a -= 2 * pi;
  if (a < 0) a += 2.0 * pi;
  return dcmp(pi - a) >= 0;
}
int main() {
  scanf("%d %lf %lf", &n, &r, &v);
  for (int i = 1; i <= n; i++) {
    scanf("%lf %lf", &s, &t);
    double l = 0.0, r = t - s - eps;
    for (int j = 1; j <= T; j++) {
      double mid = (l + r) / 2.0;
      if (check(mid))
        r = mid;
      else
        l = mid;
    }
    printf("%.9f\n", l / v);
  }
  return 0;
}
