#include <bits/stdc++.h>
using namespace std;
using db = double;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  cout.setf(ios::fixed), cout << setprecision(10);
  int n;
  db r, v;
  cin >> n >> r >> v;
  v /= r;
  while (n--) {
    db s, t;
    cin >> s >> t;
    db l = t - s;
    l /= r;
    db st = 0, en = 1e10;
    for (int times = 0; times < 100; times++) {
      db md = (st + en) / 2;
      db a = cos(md) - 1, b = sin(md), c = l - md;
      if (sqrt(a * a + b * b) < c)
        st = md;
      else
        en = md;
    }
    cout << st / v << endl;
  }
}
