def menu():
    while True:
        print('Please choose one of the following options: ')
        print('1. Read a file numbers')
        print('2. Sort the numbers from file')
        print('3. Quit the program\n')

        command = int(input("Enter a command: "))

        if command == 1:
            print("Reading the file numbers.txt")
            valid = False
            try:
                f = open('numbers', 'r')
                valid = True
            except IOError:
                print("That file does not exist!")
            if valid:
                numbers(f)
                f.close()

        elif command== 2:
            heap_sort(heap[1:])

        elif command == 3:
            print('Program is now terminating')
            break

        else:
            print("Invalid input number.\n")

def numbers(nums):
    test=[]
    for _ in nums:
        test += _.split()
    for i in test:
        heap_insert(heap,int(i))
    print("All numbers have been inserted")