//My Solution

function getLetter(s){ let letter;

                switch(s[0]){
                        case 'a' : 
                        case 'e' :
                        case 'i' : 
                        case 'o' :
                        case 'u' :
                                    letter = 'A';
                                    break;
                        case 'b' :
                        case 'c' :
                        case 'd' :
                        case 'f' :
                        case 'g' :
                                    letter = 'B';
                                    break;
                        case 'h' :
                        case 'j' :
                        case 'k' :
                        case 'l' :
                        case 'm' :
                                    letter = 'C';
                                    break;
                        default:
                                    letter = 'D';
                                    break;
            }
            return letter;
}