N = int(input())
lsA = list(map(int,input().split()))
cntall = N*(N+1)//2
cnt = 0
for i in range(N):
    if lsA[i] == 1:
        cnt += 1
    else:
        cntall -= cnt*(cnt+1)//2
        cnt = 0
cntall -= cnt*(cnt+1)//2
print(cntall)