#include <bits/stdc++.h>
using namespace std;
int n, r, v;
double f(double t) {
  return (t * v - r * sin((t * v) / r + 3.141592653589793238462643));
}
double f2(double t) { return (t * v - r * sin((t * v) / r)); }
double f3(double t) {
  return (t * v - r * sin((t * v) / r + 3.141592653589793238462643 / 2));
}
double solve(double vl) {
  double l = 0;
  double r = 1000000000.0;
  while (r - l > 1e-8 && (r - l) / r > 1e-8) {
    double c = (r + l) / 2;
    if (f(c) > vl) {
      r = c;
    } else {
      l = c;
    }
  }
  return r;
}
double solve3(double vl) {
  double l = 0;
  double r = 1000000000.0;
  while (r - l > 1e-8 && (r - l) / r > 1e-8) {
    double c = (r + l) / 2;
    if (f3(c) > vl) {
      r = c;
    } else {
      l = c;
    }
  }
  return r;
}
double solve2(double vl) {
  double l = 0;
  double r = 10000000000;
  while (r - l > 1e-8 && (r - l) / r > 1e-8) {
    double c = (r + l) / 2;
    if (f2(c) > vl) {
      r = c;
    } else {
      l = c;
    }
  }
  return r;
}
int main() {
  cin >> n >> r >> v;
  for (int i = 0; i < n; i++) {
    int f, s;
    scanf("%d", &s);
    scanf("%d", &f);
    double res = solve((1.0 * (f - s) / 2)) * 2;
    double res2 = solve2((1.0 * (f - s) / 2)) * 2;
    cout.precision(10);
    cout << min(min(res, res2), 1000000000.0) << "\n";
  }
}
