#include <bits/stdc++.h>
double solve(double y) {
  double lo = 0, hi = 3.14159265359;
  for (int i = 0; i < 70; i++) {
    double mid = (lo + hi) / 2;
    if (mid + sin(mid) < y) {
      lo = mid;
    } else {
      hi = mid;
    }
  }
  return lo;
}
int main() {
  double r, v, x, y, dist, cycles, ans, c, t, p, pt;
  int n;
  scanf("%d %lf %lf", &n, &r, &v);
  p = 2 * r * 3.14159265359;
  pt = p / v;
  for (int i = 0; i < n; i++) {
    scanf("%lf %lf", &x, &y);
    dist = y - x;
    cycles = floor(dist / p);
    ans = cycles * pt;
    dist -= p * cycles;
    c = dist * 3.14159265359 / p;
    t = solve(c);
    ans += t * pt / 3.14159265359;
    printf("%.9lf\n", ans);
  }
  return 0;
}
