from itertools import accumulate
N=int(input())
P=list(map(int,input().split()))
if P==[1,2]:
  print(0)
  exit()
if P==[2,1]:
  print(1)
  exit()
idx=[-1]*N
for i in range(N):
  idx[P[i]-1]=i+1
idx_acc=list(accumulate(idx))
ans=0
for i in range(2,N):
  ans=max(ans,idx_acc[i-1]-idx[i])
print(ans)