import java.util.Scanner;

public class B_HamburgerAndNattoRice {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = sc.nextLong();
        long N = sc.nextLong();
        long M = sc.nextLong();

        long lunch;
        if (A <= B) {
            long d = B - A;
            lunch = A + d / (M + 1);
        } else {
            long d = A - B;
            lunch = B + d / (N + 1);
        }
        System.out.println(lunch);
    }
}