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

print(total-h)