Consider this Bash script:

```
#!/bin/bash
echo Enter any character
read char
case $char in
    [a-z]) echo Lower case letter
            ;;
    [A-Z]) echo Upper case letter
            ;;
    [0-9]) echo Number
            ;;
    ?) echo Special char
            ;;
    *) echo You entered more than one character 
            ;;
esac

```

If I enter 'a', the output is *Lower case letter*, and it is the same for 'A'... How do I overcome this?