```
import.java.util.Scanner;

public class Test{
   public static void main(String[] args){
   Scanner sc = new Scanner(System.in)
   String operation = sc.nextLine();
   }
}

```

When I want to see, if the string operation contains certain letters, I could write f.ex.

```
    if(operation.contains("a") || operation.contains("b")){
        System.out.println("This is not a valid choice. Please retry!");
    }

```

But I want to know what to write, if the string contains letters, e.g. from a to k. If I write it with || every single time, it's not efficient.
EDIT: I'm only allowed to use the methods contains and equals.