#include <bits/stdc++.h>
using namespace std;
template <class T>
int getbit(T s, int i) {
  return (s >> i) & 1;
}
template <class T>
T onbit(T s, int i) {
  return s | (T(1) << i);
}
template <class T>
T offbit(T s, int i) {
  return s & (~(T(1) << i));
}
template <class T>
int cntbit(T s) {
  return __builtin_popcount(s);
}
template <class T>
T gcd(T a, T b) {
  T r;
  while (b != 0) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
template <class T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
int n;
double r, v, x;
double cc(double x) {
  double t = x / (2 * acos(0) + 2 * acos(0));
  return x - ((long long)(t)) * (2 * acos(0) + 2 * acos(0));
}
bool cal(double d) {
  double g = cc(d / r) / 2;
  return d + sin(g) * 2 * r >= x;
}
int main() {
  cin >> n >> r >> v;
  for (int run = 0; run < (n); ++run) {
    double x1, x2;
    scanf("%lf %lf", &x1, &x2);
    x = x2 - x1;
    double l = 0, R = x, mid;
    for (int RR = 0; RR < (100); ++RR) {
      mid = (l + R) / 2;
      if (cal(mid))
        R = mid;
      else
        l = mid;
    }
    printf("%.9lf\n", l / v);
  }
  return 0;
}
