def print_list1(list_to_print):
    '''print out the indices and elements of list_to_print'''
    for index in range(0, len(list_to_print)):
        element = list_to_print[index]
        print("list item {0} is {1}".format(index, element))
        

def print_list2(list_to_print):
    '''print out the indices and elements of list_to_print
    using an enumerate object'''
    for (index, element) in enumerate(list_to_print):
        print("list item {0} is {1}".format(index, element))


def years_to_100k():
    '''return the numbers of years until Bowdoin tuition
    is expected to exceed 100k.'''

    years_passed = 0 # number of years that have passed
    cost = 61354 # 2015-16 cost
    annual_increase = 0.0386 # average annual increase

    while cost < 100000:
        cost *= 1 + annual_increase
        years_passed += 1
        print("Cost in year", years_passed, "is", cost)

    return years_passed


def printlist_range(data):
    '''print a list using a range loop'''
    for i in range(0, len(data)):
        print(data[i])


def printlist_while(data):
    '''print a list using a while loop'''
    index = 0
    while index < len(data):
        print(data[index])
        index += 1


def gcd(num1, num2):
    '''return the GCD of num1 and num2'''
    x = max(num1, num2)
    y = min(num1, num2)
    r = x % y
    while r != 0:
        x = y
        y = r
        r = x % y
    return y


def prompt_gcd():
    '''Repeatedly prompts the user for 2 numbers, and prints
    the gcd of those 2 numbers. Stops if 'exit' is entered
    for the first number.'''
    finished = False
    while not finished:
        num1 = input('Input some number: ')
        if num1 == 'exit':
            # set flag to end while loop
            finished = True
        else:
            num2 = input('Input another number: ')
            # convert input strings to ints
            result = gcd(int(num1), int(num2))
            print("The GCD of", num1, "and", num2, "is", result)