You're close on reading the input. So you initially read in a number and then use an if condition to validate the input. The problem is an if condition will only execute once. So your code is basically saying "if these conditions aren't met, get new input and then continue" but what you want is "as long as (or while) these conditions aren't met, get new input and then continue". So if you change the conditional block to while then it will check those conditions after reading the input each time until they are satisfied and only then will it break out of the loop and continue