#include <bits/stdc++.h>
int MOD = int(1e9) + 7;
inline int add(int a, int b) {
  return (a + b >= MOD) ? (a + b - MOD) : (a + b);
}
inline void inc(int &a, int b) { a = add(a, b); }
inline int sub(int a, int b) { return (a - b < 0) ? (a - b + MOD) : (a - b); }
inline void dec(int &a, int b) { a = sub(a, b); }
inline int mul(int a, int b) { return (a * 1ll * b) % MOD; }
using namespace std;
const long double PI = acosl(-1);
int n, r, v;
long double f(long double t) { return r * cosl(-PI / 2 - t * v / r) + v * t; }
long double search(long double x, long double from, long double to) {
  for (int i = 0; i < 100; i++) {
    double middle = (from + to) / 2;
    if (f(middle) < x)
      from = middle;
    else
      to = middle;
  }
  return from;
}
int main() {
  scanf("%d %d %d", &n, &r, &v);
  while (n--) {
    int s, e;
    scanf("%d %d", &s, &e);
    long double delta = e - s, length = 2 * PI * r, mod = fmodl(delta, length),
                t = length / v,
                ans = (delta - mod) / v + search(PI * r + mod / 2, 0, t) -
                      search(PI * r - mod / 2, 0, t);
    printf("%.12f\n", (double)ans);
  }
  return 0;
}
