n = int(input())
a = list(map(int, input().split()))
ans = 0
tmp = 0
for i in range(n):
	if a[i]:
		tmp += 1
	else:
		ans += tmp*(tmp+1)//2
		tmp = 0
if a[-1]:
	ans += tmp*(tmp+1)//2
print(n*(n+1)//2 - ans)