N = int(input())
A = list(map(int,input().split()))
ans = N*(N+1)//2
now = -1
flg = False
for i in range(N):
  if A[i] == 1:
    if flg == False:
      now = i
      flg = True
    ans -= (i-now+1)
  else:
    flg = False
    now = i

print(ans)