#include <bits/stdc++.h> using namespace std; #define endl "\n" #define int long long void f(int n, char a, char b, char c) { if (n == 0) { return; } else { f(n - 1, a, c, b); cout << a << " " << c << endl; f(n - 1, b, a, c); } } void solve() { int n...