SecondSoluition

function secondSolution(num) {
    const isNumeric = (leftInteger) => /^[0-9]*$/.test(leftInteger);

    if (isNumeric(num) === false) {
        throw 'Invaid Argument!';
    }

    const format = {
        under: ['', '일', '이', '삼', '사', '오', '육', '칠', '팔', '구'],
        overTenUnderThousend: ['', '십', '백', '천', ],
        overThousendUnderTrillion: ['', '만', '억', '조'],
    };

    let rlt = [];
    let splitStrByLen = String(num).split('').reverse()
        .join('')
        .match(/.{1,4}/g);
    let rltIdx = 0;
    splitStrByLen.forEach((v, i) => {
        let formatIdx = 0;
        v.split('').forEach((splitValue, splitIdx) => {
            if (typeof (format.under[splitValue]) == 'undefined' || format.under[splitValue]) {
                rlt[rltIdx] = `${format.under[splitValue]}${format.overTenUnderThousend[splitIdx]}`;
                if (formatIdx === 0) {
                    rlt[rltIdx] = `${rlt[rltIdx]}${format.overThousendUnderTrillion[i]}`;
                }
                formatIdx++;
            }
            rltIdx++;
        });
    });
    return rlt.reverse().join('');
}


const readline = require("readline");
const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

rl.on("line", function (line) {
    console.log(secondSolution(String(line)));
    rl.close();
}).on("close", function () {
    process.exit();
});