#include <bits/stdc++.h>
#pragma comment(linker, "/stack:16777216")
using namespace std;
const int INF = 1000000000;
const int MAX = 200007;
const int MAX2 = 1000000;
const int MAXD = 20;
const int BASE = 1000000007;
const int MOD = 1000000007;
int main() {
  int n;
  cin >> n;
  double r, v;
  cin >> r >> v;
  for (int i = (0); i < (n); i++) {
    int s1, s2;
    scanf("%d%d", &s1, &s2);
    double l = s2 - s1;
    int cnt = l / (2 * 3.14159265358979 * r);
    l -= cnt * 2 * 3.14159265358979 * r;
    double L = 0;
    double R = 1e17;
    for (int it = (0); it < (147); it++) {
      double X = (L + R) / 2;
      double f = v * X + 2 * r * sin(0.5 * v / r * X);
      if (f > l)
        R = X;
      else
        L = X;
    }
    printf("%.10f\n", L + cnt * 2 * 3.14159265358979 * r / v);
  }
  return 0;
}
