N = int(input())
A = list(map(int,input().split()))
L = 0
cand = []
flg = 0
for i in range(N):
    if A[i] == 1 and L == 0:
        st = i
        L += 1
        flg = 1
    elif A[i] == 0:
        if flg == 1:
            flg = 0
            L += 1
        else:
            cand.append(L)
            L = 0
    elif A[i] == 1 and flg == 0:
        L += 1
        flg = 1
    else:
        st = i
        cand.append(L)
        L = 1
        flg = 1
cand.append(L-1)
ans = 0
for i in cand:
    if i%2 == 1:
        ans += ((i+1)//2)**2
    else:
        m = i//2
        ans += m*(m+1)
print(ans)
#print(cand)