跳一跳201803-1

#include<iostream>
using namespace std;

int main()
{
int n;
cin>>n;
int sum=0;
int point=0;
while(n!=0)
{
if(n==2)
point+=2;
else
point=0;
switch(n){
case 1:sum+=1;break;
case 2:sum+=point;
}

cin>>n;
}
cout<<sum<<endl;


return 0;
}