#include<cstdio>
const int M = 30;
int a[M+1][2];//第一维用于读入，第二维用于记录上一局得分 int main(){int temp,index=0,ans=0;scanf("%d",&temp);while(temp!=0){a[index][0]=temp;if(a[index][0]==1){ans+=1;}else{if(a[index-1][0]==2){a[index][1]=a[index-1][1]+2;}else{a[index][1]=2;}ans+=a[index][1];}index++;scanf("%d",&temp);}	printf("%d",ans);return 0;
}