n = int(input())
a = list(map(int, input().split()))

lis = []
tmp = []
for i in range(n):
    if i == 0:
        former = a[0]
        tmp.append(a[0])
    else:
        if former != a[i]:
            tmp.append(a[i])
            former = a[i]
        else:
            lis.append(tmp)
            tmp = []
            tmp.append(a[i])
            former = a[i]

if tmp != []:
    lis.append(tmp)
ans = 0
cnt = 0
for i in range(len(lis)):
    if i != len(lis) - 1:
        for j in range(len(lis[i])):
            if a[cnt] == 1:
                ans += len(lis[i]) - j
            cnt += 1
    else:
        for j in range(len(lis[i])):
            if a[cnt] == 1:
                ans += len(lis[i]) - (j + 1)
            cnt += 1

print(ans)