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

import sys

ans = 0
right = 0
for left in range(N):
    while right < N and A[right] == 1:
        right += 1
    if right == N:
        print(ans)
        exit()
    ans += N - right
    if left == right:
        right += 1
print(ans)