#include <bits/stdc++.h>
using namespace std;
int n, R, v;
int main() {
  scanf("%d %d %d", &n, &R, &v);
  for (int ni = 0; ni < n; ni++) {
    int s, f;
    scanf("%d %d", &s, &f);
    double y = (f - s) / 2.0 / R;
    double l = 0, r = y + 1;
    for (int i = 0; i < 60; i++) {
      double mid = (l + r) / 2;
      if (mid + abs(sin(mid)) < y)
        l = mid;
      else
        r = mid;
    }
    printf("%.9f\n", l * 2 * R / v);
  }
}
