멀쩡한사각형

function solution(w, h) {
 
    function GCD(w,h){
        let mod = w%h
        if( mod === 0){
           return h
        }
        else return GCD(h,mod)
    }

    let gcd = GCD(w,h)
    
    return w*h-(w+h-gcd)
       
}