#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  double r, v;
  scanf("%d %lf %lf", &n, &r, &v);
  double k = v / r;
  while (n--) {
    double s, f;
    scanf("%lf %lf", &s, &f);
    double len = (f - s) / 2.0;
    double ans = 1e9;
    double lt = 0.0, rt = 1e9;
    for (int i = 0; i < 100; i++) {
      double mt = (lt + rt) / 2.0;
      double f = v * mt - r * sin(k * mt);
      if (f < len)
        lt = mt;
      else
        rt = mt;
    }
    ans = min(ans, lt);
    lt = 0.0, rt = 1e9;
    for (int i = 0; i < 100; i++) {
      double mt = (lt + rt) / 2.0;
      double f = v * mt + r * sin(k * mt);
      if (f < len)
        lt = mt;
      else
        rt = mt;
    }
    ans = min(ans, lt);
    printf("%.12f\n", ans * 2);
  }
  return 0;
}
