#include <bits/stdc++.h>
using namespace std;
const long double eps = 1e-13;
const long double PI = acos(-1);
const int INF = (int)1e9;
const long long INFF = (long long)1e18;
const int mod = (int)1e9 + 7;
const int MXN = (int)1e6 + 7;
int main() {
  int n;
  long double r, v;
  scanf("%d %Lf %Lf", &n, &r, &v);
  while (n--) {
    long long d1, d2;
    scanf("%lld %lld", &d1, &d2);
    long double d = d2 - d1;
    d /= 2;
    long double ll = 0, rr = INF;
    int t = 100;
    while (t--) {
      long double mid = (ll + rr) / 2;
      long double x = mid * v;
      x += r * cos(PI / 2 - mid * v / r);
      if (x > d)
        rr = mid;
      else
        ll = mid;
    }
    long double ans = rr;
    ll = 0, rr = INF;
    t = 100;
    while (t--) {
      long double mid = (ll + rr) / 2;
      long double x = mid * v;
      x += r * cos(PI * 3 / 2 - mid * v / r);
      if (x > d)
        rr = mid;
      else
        ll = mid;
    }
    ans = min(ans, rr);
    printf("%.13Lf\n", ans * 2);
  }
  return 0;
}
