N = int(input())
A = list(map(int,input().split()))

S = [0] * N
now = 0
end = 0
while now < N - 1:
    if A[now] == 0:
        S[now] = 0
        now += 1
        continue
    for i in range(now,N-1):
        if A[i+1] == A[i]:
            end = i+1
            break
    for i in range(now,end,2):
        S[i] = end - i
    now = end
sum = 0
for i in range(N):
    sum += S[i]
print(sum)
    
#多分ok