N = int(input())
ans = N * (N + 1)
seq = input()
d = 0
for c in seq:
    if c == ' ':
        continue
    if c == '0':
        ans -= d * (d + 1)
        d = 0
    else:
        d += 1
ans -= d * (d + 1)
ans //= 2
print(ans)