def run_length_compress(string):
    string = string + ["@"]
    n = len(string)

    begin = 0
    end = 1
    cnt = 1
    ans = []
    while True: 
        if end >= n:
            break
        if string[begin] == string[end]:
            end += 1
            cnt += 1
        else: 
            ans.append((cnt, string[begin]))
            begin = end
            end = begin + 1
            cnt = 1 
    
    return ans

n = int(input())
a = list(map(int, input().split()))

run_a = run_length_compress(a)
last = False
ans = 0
for num, _ in run_a:
    if last:
        if num == 1:
            last = False
        else:
            ans += num - 1
            last = True
    else:
        if num == 1:
            ans += 1
            last = True
        else:
            ans += num
            last = True
print(ans)