#include<bits/stdc++.h> using namespace std; long sum;int n; void dfs(int from,int cur,int deep){ if(deep==n){ if(cur!=from) sum++; if(n==1) sum++; return ; } for(int i=0;i<=2;i++){ if(i!=cur) dfs(from,i,deep+1); } } int main(){ while(cin>>n){ sum=0; for(int i=0;i<=2;i++){ dfs(i,i,1); } cout<<sum<<endl; } } |
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