hdu 2018

#include<iostream>using namespace std;int main(){    int n;    while(cin>>n&&n!=0){                    int m=1,tree=0,two=0,one=0;        for(int i=1;i<n;i++){            m=m+tree;            tree=two;            two=one;            one=m;        }cout<<m+tree+two+one<<endl;    }    return 0;}