let today = new Date(year, month, day);
let day = today.getDay();
day === 0
? console.log('SUN')
:day === 1
?console.log('MON')
:day === 2
?console.log('TUE')
:day === 3
?console.log('WED')
:day === 4
?console.log('THU')
:day === 5
?console.log('FRI')
:console.log('SAT')
const gcd = (a, b) => a % b === 0 ? b : gcd(b, a % b);
const lcm = (a, b) => a * b / gcd(a, b);