Write python program which repeatedly reads positive numbers until the user enters -1. once -1 is entered, print out both the maximum and minimum of the numbers

print ('Hello World')
maximum=None
minimum=None
while True:
    number=int(input('enter a positive number:'))
    if number==-1:
        break
    elif number<-1:
        continue
    if maximum ==None or number>maximum:
        maximum=number
    if minimum ==None or number<minimum:
        minimum=number
    print('minimum is :',minimum)
print('highest entered number is :',maximum)
print('lowest entered number is :',minimum)