멀쩡한사각형

import java.util.*;
import java.math.*;
class Solution {
    public long solution(int w, int h) {
        int gcd = BigInteger.valueOf(w).gcd(BigInteger.valueOf(h)).intValue();
        return ((long)w*(long)h)-(((long)(w/gcd)+(long)(h/gcd-1)))*gcd;
    }
}