201803-1 跳一跳

#include <iostream>
using namespace std;
int main(){
	int n;
	int sum=0,temp=0;
	while(cin>>n&&n){
		sum=sum+n;
		if(n==1)  {
			temp=0;
		}
		if(n==2){
			sum=sum+temp;
			temp+=2;
		}
	}
	cout<<sum;
	return 0;
}