#include <stdio.h>
#include <math.h>

int num[50];
int main(){
	int signal = 0;
	int symbol = 0;
	int cnt = 0;
	while(scanf("%d",&num[signal]) != EOF,num[signal]){
		if((signal == 0 || num[signal - 1] == 1) && num[signal] == 2){
			cnt = cnt + 2;
			symbol = 1;
		}
		else if(num[signal] == 1){
			cnt = cnt + 1;
			symbol = 0;   //遇到1就重头算 
		}
		else if(num[signal] == 2 && num[signal - 1] == 2){
			symbol++;
			cnt = cnt + 2*symbol;
		}
		signal++;
	}
	printf("%d",cnt);
}