The user enters from the keyboard a six-digit integer. Write a program that determines whether the entered number is a lucky number (the lucky number is a six-digit number, in which the sum of the...

The user enters from the keyboard a six-digit integer. Write a program that determines whether the entered number is a lucky number (the lucky number is a six-digit number, in which the sum of the first three numbers equals to the sum of other three numbers). If the user entered not a six-digit integer, an error message is output.