#include <bits/stdc++.h>
#pragma warning(disable : 4996)
using namespace std;
inline double ff(double x) { return x - sin(x); }
double finv(double x) {
  double l = 0;
  double u = 2 * 3.1415926535897932384626433832795;
  for (int i = 0; i < 100; i++) {
    double m = (l + u) / 2;
    if (ff(m) > x) {
      u = m;
    } else
      l = m;
  }
  return (u + l) / 2;
}
int main() {
  int n, r, v;
  scanf("%d %d %d", &n, &r, &v);
  double w = (double)v / r;
  for (int i = 0; i < n; i++) {
    int s, f;
    scanf("%d %d", &s, &f);
    double dist = ((double)f - s) / r;
    int q = (int)floor(dist / 2 / 3.1415926535897932384626433832795);
    double rem = dist - q * 2 * 3.1415926535897932384626433832795;
    double p1 = finv(rem / 2);
    p1 = p1 * 2 + q * 2 * 3.1415926535897932384626433832795;
    double p2 = finv((2 * 3.1415926535897932384626433832795 - rem) / 2);
    p2 = (q + 1) * 2 * 3.1415926535897932384626433832795 - 2 * p2;
    printf("%.15f\n", min(p1, p2) / w);
  }
  return 0;
}
