#include <bits/stdc++.h>
using namespace std;
template <class F, class T>
T convert(F a, int p = -1) {
  stringstream ss;
  if (p >= 0) ss << fixed << setprecision(p);
  ss << a;
  T r;
  ss >> r;
  return r;
}
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;
}
template <class T>
T sqr(T x) {
  return x * x;
}
template <class T>
T cube(T x) {
  return x * x * x;
}
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 s == 0 ? 0 : cntbit(s >> 1) + (s & 1);
}
const long double PI = acos(-1.0);
const long double eps = 1e-9;
const int dr[] = {-1, 0, +1, 0, -1, -1, +1, +1};
const int dc[] = {0, +1, 0, -1, -1, +1, -1, +1};
const int inf = (int)1e9 + 5;
const long long linf = (long long)1e16 + 5;
const long long mod = (long long)1e9 + 7;
const int MX = (int)2e6 + 5;
long long n;
long double r, v, kc;
int main() {
  std::ios::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> r >> v;
  long double left, right, mid;
  for (int k = (1); k <= (n); ++k) {
    long long s, f;
    cin >> s >> f;
    kc = f - s;
    left = 0;
    right = kc / v;
    for (int i = (1); i <= (100); ++i) {
      mid = (left + right) / 2;
      long double dd = mid * v;
      long double over = dd - floor(dd / (2 * PI * r)) * (2 * PI * r);
      over /= 2.0;
      long double maxx = dd + 2 * sin(over / r) * r;
      if (maxx >= kc)
        right = mid;
      else
        left = mid;
    }
    cout << fixed << setprecision((10)) << (mid);
    cout << '\n';
  }
}
