import sys

n = int(input())
nums = input().split(' ')
nums = [int(i) for i in nums]

result = 0
for n in range(len(nums)):
    if n == 0:
        result = nums[n]
    else:
        if nums[n] == 1 and nums[n-1] == 1:
            result += 2
        elif nums[n] == 1:
            result += 1
print(result)