#include <bits/stdc++.h>
using namespace std;
long n;
double r, v, t;
double x, y;
bool ok(double m) {
  double tmp;
  tmp = v * m + r * fabs(sin(v * m / r));
  return (tmp > (y / 2 - 1e-9));
}
double sol() {
  double res, lo, hi, mid;
  lo = 0;
  hi = 2e9;
  for (int i = 1; i <= 100; i++) {
    mid = (lo + hi) / 2;
    if (ok(mid)) {
      res = mid;
      hi = mid;
    } else
      lo = mid;
  }
  return res * 2;
}
int main() {
  scanf("%ld%lf%lf", &n, &r, &v);
  t = acos(-1.0) / v;
  for (int i = 1; i <= n; i++) {
    scanf("%lf%lf", &x, &y);
    y = y - x;
    printf("%.10lf\n", sol());
  }
  return 0;
}
