Titu and Sweety

After Titu's breakup with Pihu, he met Sweety and they both fell in love instantly but Sweety wants to test the knowledge of Titu so she asks him a simple question but since Titu is too anxious and does not want to take any chances, he asks you for help. You are given a string and $n$ characters. The string is called good if it contains all the $n$ characters atleast once, else it is called a bad