#include <bits/stdc++.h>
using namespace std;
double f(double d) {
  double pi = 2 * acos(0.0);
  double times = floor(d / (2 * pi));
  double res = times * 2 * pi;
  d -= res;
  double Min = 0, Max = pi;
  int i;
  for (i = (0); i < (128); ++i) {
    double Mid = (Max + Min) / 2;
    double len = 2 * (Mid + sin(Mid));
    if (len >= d)
      Max = Mid;
    else
      Min = Mid;
  }
  return (res + 2 * Max);
}
int main() {
  int n, r, v;
  scanf("%d%d%d", &n, &r, &v);
  int i;
  for (i = (0); i < (n); ++i) {
    int ss, ff;
    scanf("%d%d", &ss, &ff);
    double d = (ff - ss + 0.0) / r;
    printf("%.11lf\n", (r * f(d)) / v);
  }
  return 0;
};
