N = int(input())
lsP = list(map(int,input().split()))
# どこで負けるか
indls = [0]*(N+1)
for i in range(N):
    indls[lsP[i]] = i+1
ans = 0
summ = 0
for i in range(1,N+1):
    val = summ-indls[i]
    ans = max(ans,val)
    summ += indls[i]
print(ans)