#include <bits/stdc++.h>
using namespace std;
int n;
double r, v, d, t, b, e, mid;
int main() {
  int n, dr, dv, bb, ee, i;
  scanf("%d%d%d", &n, &dr, &dv);
  r = dr, v = dv;
  while (n--) {
    scanf("%d%d", &bb, &ee);
    d = ee - bb;
    e = d / r;
    b = e - 2 * 3.14159265359;
    if (b < 0) b = 0.0;
    for (i = 0; i < 50; i++) {
      mid = (b + e) * 0.5;
      t = sin(mid * 0.5);
      if (t < 0) t = -t;
      t = r * mid + 2 * r * t;
      if (t < d)
        b = mid;
      else
        e = mid;
    }
    printf("%.10lf\n", b * r / v);
  }
}
