def give_back(amount):
    thao = 1000
    punch = 500
    rwabe = 200
    soo = 100
    chwani = 50
    mbao = 20
    ashu = 10
    ngovo = 5
    bob = 1
    remaining = 0
    balance = None
    if amount < thao:
        balance = (amount // thao) * 1000
        remaining = amount % thao
        if remaining > punch
