N = int(input())
A = [0]+list(map(int, input().split()))
B = [0]*(N+1)
for i in range(N+1):
    B[A[i]] = i

ans = 0
s = -B[1]
for i in range(2, N+1):
    s += 2*B[i-1]-B[i]
    ans = max(ans, s)

print(ans)