#include <bits/stdc++.h>   using namespace std;   const double pi = acos(-1.0);   int main() {     double s, f, r, v;     int n;     scanf( %d%lf%lf , &n, &r, &v);     while (n--) {       scanf( %lf%lf , &s, &f);       double ans = 0, d = f - s;       int cnt = (int)floor(d / (2 * pi * r));       ans += cnt * 2 * pi * r / v;       d -= cnt * (2 * pi * r);       d /= 2;       double L = 0, R = d;       for (int _i = 0; _i < 60; _i++) {         double mid = (L + R) / 2;         if (mid + sin(mid / r) * r > d)           R = mid;         else           L = mid;       }       ans += 2 * L / v;       printf( %f n , ans);     }     return 0;   }   