import sys
readline=sys.stdin.readline

N=int(readline())
A=list(map(int,readline().split()))
ans=N*(N+1)//2
L,R=[0],[]
for i in range(1,N+1):
    if A[i-1]==0:
        L.append(i)
for i in range(N):
    if A[i]==0:
        R.append(i)
R.append(N)
for l,r in zip(L,R):
    d=r-l
    ans-=d*(d+1)//2
print(ans)