def find_loop_size( public_key, subject=7 ):
    """
    To transform a subject number, start with the value 1. 
    
    Then, a number of times called the loop size, perform the following steps:
        - Set the value to itself multiplied by the subject number.
        - Set the value to the remainder after dividing the value by 20201227
    
    After the desired loop size, the subject number 7 is transformed into the 
    public key itself.
    """
    loops = 0
    value = 1
    while value != public_key:
        loops += 1
        value *= subject
        value = value % 20201227
    return loops