def main():
    import sys
    input = sys.stdin.readline
    
    N = int(input())
    P = list(map(int,input().split()))
    count = 0
    sum = [0 for _ in range(N)]
    for i in range(N):
        sum[P[i]-1] = i + 1
    for i in range(1,N):
        sum[i] += sum[i-1]

    for i in range(N):
        if i == 0:
            count = max(count,0)
            continue
        count = max(count,sum[i-1]-(sum[i]-sum[i-1]))
    print(count)

if __name__ == '__main__':
    main()