#include<bits/stdc++.h> using namespace std; int s=1; void hnt(int n,char a,char b,char c){ if(n==0) return; hnt(n-1,a,c,b); cout<<s<<":"<<a<<"->"<<c<<endl; s++; hnt(n-1,b,a,c); } int main(){ int n; cin>>n; hnt(n,'a','b','c'); return 0; }