[Level 2] 멀쩡한 사각형

class Solution {
    public long solution(int w, int h) {
        long wl = (long)w; long hl = (long)h;
        return wl*hl-wl-hl+gcd(wl,hl);
    }
    
    public long gcd(long w, long h) {
        if(h==0) { return w; }
        
        return gcd(h, w%h);
    }
}