#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void Read(T &x) {
  int f = 1;
  char t = getchar();
  while (t < '0' || t > '9') {
    if (t == '-') f = -1;
    t = getchar();
  }
  x = 0;
  while (t >= '0' && t <= '9') {
    x = x * 10 + t - '0';
    t = getchar();
  }
  x *= f;
}
template <class T>
inline void chkmin(T &x, T y) {
  if (x > y) x = y;
}
template <class T>
inline void chkmax(T &x, T y) {
  if (x < y) x = y;
}
const int maxn = 100005;
const double pi = acos(-1.0);
int n;
int r;
int v;
int s;
int f;
double prs;
void input() {
  Read(n);
  Read(r);
  Read(v);
}
bool check(double t) {
  double ang = pi * (fmod(t, prs) / prs);
  return v * t + 2 * sin(ang) * r >= f - s;
}
void solve() {
  while (n--) {
    Read(s);
    Read(f);
    double l = 0;
    double r = 1e10;
    double mid;
    prs = (2 * pi * ::r) / v;
    int trial = 100;
    while (trial--) {
      mid = (l + r) / 2;
      if (check(mid)) {
        r = mid;
      } else {
        l = mid;
      }
    }
    printf("%.10f\n", (l + r) / 2);
  }
}
int main() {
  input();
  solve();
  return 0;
}
