#include <bits/stdc++.h>
using namespace std;
#pragma comment(linker, "/STACK:1024000000,1024000000")
int Scan() {
  int res = 0, flag = 0;
  char ch;
  if ((ch = getchar()) == '-')
    flag = 1;
  else if (ch >= '0' && ch <= '9')
    res = ch - '0';
  while ((ch = getchar()) >= '0' && ch <= '9') res = res * 10 + (ch - '0');
  return flag ? -res : res;
}
void Out(int a) {
  if (a < 0) {
    putchar('-');
    a = -a;
  }
  if (a >= 10) Out(a / 10);
  putchar(a % 10 + '0');
}
const int N = 100005;
int n;
double s, f, r, v;
bool check(double t) {
  double S = v * t, l = 2 * acos(-1.0) * r;
  double ss = S - floor(S / l) * l;
  double T = S + fabs(sin(ss / 2 / r)) * 2 * r;
  return T >= f - s;
}
int main() {
  scanf("%d%lf%lf", &n, &r, &v);
  while (n--) {
    scanf("%lf%lf", &s, &f);
    double l = 0, r = 1e12;
    int tot = 100;
    while (tot--) {
      double mid = (l + r) / 2;
      if (check(mid))
        r = mid;
      else
        l = mid;
    }
    printf("%.7lf\n", l);
  }
  return 0;
}
