loop = 3
n = True
while n:
    try:
        choice = int(raw_input('You choice: '))
    except ValueError:
        print 'ERROR: "{0}" not integer'.format(choice)
        loop -= 1
    else:
        if choice != 1 or choice != 2 or choice != 3 or choice != 4:
            print 'ERROR: "{0}" must be [1:4]'.format(choice)
            loop -= 1
        else:
            if choice == 4:
                import sys
                print 'By by'
                sys.exit(1)
            n = False
    if loop == 0:
        import sys
        print 'By by'
        sys.exit(1)

if choice not in (1,2,3,4):