N = int(input())
P = list(map(int,input().split()))

import sys
if N == 1:
    print(0)
    exit()

ans = 0
point = 0
D = {v:i + 1 for i,v in enumerate(P)}
for i in range(1,N):
    point += D[i]
    if point - D[i+1] > ans:
        ans = point - D[i+1]
print(ans)