CCF|跳一跳

import java.util.Scanner;

public class Main
{
public static void main (String[] args)
{
Scanner scanner=new Scanner(System.in);
int score=0;
int sum=0;
int n=0;
while((n=scanner.nextInt())!=0)
{

        if(n==1)
        {
            score=1;
        }
        else if(n==2&&score%2!=0)
        {
            score=2;
        }
        else if(n==2&&score%2==0)
        {
            score+=2;
        }
        sum+=score;
    }
    System.out.println(sum);
}

}