def is_happy_number(n):

    # Helper function that calculates the sum of squared digits.
    def sum_of_squared_digits(number):
        total_sum = 0
        while number > 0:
            number, digit = divmod(number, 10)
            total_sum += digit ** 2
        return total_sum

    slow_pointer = n 
    fast_pointer = sum_of_squared_digits(n)  

    while fast_pointer != 1 and slow_pointer != fast_pointer: 
        slow_pointer = sum_of_squared_digits(slow_pointer)
        fast_pointer = sum_of_squared_digits(sum_of_squared_digits(fast_pointer))

    if(fast_pointer == 1):
        return True
    return False


def main():
    inputs = [1, 5, 19, 25, 7]
    for i in range(len(inputs)):
        print(i+1, ".\tInput Number: ", inputs[i], sep="")
        print("\n\tIs it a happy number? ", is_happy_number(inputs[i]))
        print("-" * 100)


if __name__ == '__main__':
    main()