题解

#include<iostream>
using namespace std;
int n;
char a,b,c;
void f(int n,char a,char b,char c){
	if(n==0){
        return;
    }
	f(n-1,a,c,b);
	cout<<a<<"->"<<n<<"->"<<b<<'\n';
	f(n-1,c,b,a);
}
int main(){
	cin>>n>>a>>b>>c;
	f(n,a,b,c);
	return 0;
}