import sys
input = sys.stdin.readline
N = int(input())
a = list(map(int, input().split()))
res = N * (N + 1) // 2
r = 0
for l in range(N):
  if a[l] == 0: continue
  if r < l: r = l
  while r < N and a[r]: r += 1
  res -= r - l
print(res)