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

c=0
l=0
for i in range(n):
    if A[i] == 1:
        continue
    t=i-l+1
    c+=t*(t-1)//2
    l=i+1

t=n-l+1
c+=t*(t-1)//2
ans=(n+1)*n//2 - c
print(ans)