n = int(input())
b = [int(i) for i in input().split()]

now = 0
ans = 0
for i in range(n):
    if b[i] == 0:
        for j in range(n):
            if b[now] >= 2:
                b[now] -= 1
                b[i] = 1
                #print(now-i,"now")
                ans += abs(now-i)
                break
            else:
                now += 1
print(ans)