n=int(input())
ns=list(map(int,input().split()))
s=0
box=[]
for i in range(n):
    if ns[i] == 1:
        s += 1
        if i == n-1:
            box.append(s)
    else:
        if s > 0:
            box.append(s)
        s=0
h=0
for i in box:
    h += (i+1)*i // 2
    
total = (n+1)*n // 2

print(total-h)