function lettersCombinations(input) {

    let startLetter = input[0].charCodeAt();
    let endLetter = input[1].charCodeAt();
    let exceptLetter = input[2].charCodeAt();
    result = "";
    let validCombinationsCount = 0;

    for (let i = startLetter; i <= endLetter; i++) {
        //result += String.fromCharCode(i) + " ";

        if (i === exceptLetter) {
            continue;
        }

        for (let j = startLetter; j <= endLetter; j++) {
            //result += String.fromCharCode(j) + " ";

            if (j === exceptLetter) {
                continue;
            }

            for (let k = startLetter; k <= endLetter; k++) {
               // result += String.fromCharCode(k) + " ";

                if (k === exceptLetter) {
                    continue;
                }
                result += String.fromCharCode(i) + String.fromCharCode(j) + String.fromCharCode(k) + " ";
                validCombinationsCount++;
            }
            //result += validCombinationsCount;
            //console.log(result);
        }
    }
    result += validCombinationsCount; //outside for loop
    console.log(result);              //outside for loop
}