#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
	int n,array[100],score=0,combo=0;
	scanf("%d",&n);
	for (int i = 0; i < n; i++)
	{
		scanf("%d", &array[i]);
		if (i != 0)
		{
			if (array[i - 1] == 1 && array[i] == 1)
			{
				score += (combo + 1);
				combo++;
			}
			else if (array[i] == 1)
			{
				score++;
				combo++;
			}
			else
				combo = 0;


		}
		else if (array[i] == 1)
		{
			score++;
			combo++;
		}	
	}
	printf("%d", score);
	
	return 0;
}