from sys import stdin

n, *a = map(int, stdin.read().split())
asort = []
for i in range(n):
    asort.append((-a[i],i+1))
asort.sort()

ans = 0
val = n * (n+1) // 2
for i in range(n):
    val -= asort[i][1]
    ans = max(ans,val-asort[i][1])
print("{}".format(ans))