#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1);
int main() {
  int n, r, v;
  scanf("%d%d%d", &n, &r, &v);
  double om = 1.0 * v / r;
  for (int i = 0; i < n; i++) {
    int s, f;
    scanf("%d%d", &s, &f);
    double lb = 0, rb = 1.0 * (f - s) / v;
    for (int j = 0; j < 100; j++) {
      double m = (lb + rb) / 2, d = v * m + fabs(2 * r * sin(om / 2 * m));
      if (d > f - s)
        rb = m;
      else
        lb = m;
    }
    printf("%.12f\n", lb);
  }
  return 0;
}
