function unusedDigits(){

    const args = [].slice.call(arguments).join('');
    const num = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
    const res = [];

    for (let numIndex = 0; numIndex < num.length; numIndex++) {
        if(args.indexOf(num[numIndex]) > -1) {
            continue;
        }

        res.push(num[numIndex]);
    }
    return res.join('');
}