N = int(input())
P = list(map(int, input().split()))
dic = {}
for i in range(N):
    dic[P[i]] = i+1
#print(dic)
total = N*(N+1)//2

if N == 1:
    ans = 0
elif N == 2:
    if P[0] == 1:
        ans = 0
    else:
        ans = 1
else:
    # numだけ負ける、それ超はドローとする
    ans = 0
    draw = 0
    for num in range(N, 0, -1):
        second = dic[num]
        first = total - second - draw
        ans = max(ans, first-second)
        draw += second
print(ans)