function getLetter(s) { let letter; // Write your code here let charAtFirst = s[0];

const set1 = ['a','e','i','o','u'];
const set2 = ['b', 'c', 'd', 'f', 'g'];
const set3 = ['h','j','k', 'l', 'm'];
const set4 = ['n','p','q','r','s','t','v','w','x','y','z'];

switch(true) 
{
    case set1.indexOf(charAtFirst) !== -1:
        letter = 'A';
        break;
    case set2.indexOf(charAtFirst) !== -1:
        letter = 'B';
        break;
    case set3.indexOf(charAtFirst) !== -1:
        letter = 'C';
        break;
    case set4.indexOf(charAtFirst) !== -1:
        letter = 'D';
        break;    
    default:
        letter = set1.indexOf(charAtFirst);    
}

return letter;

}