import java.util.*;

public class restaurante {
    public static void main( String[] args ){
        Scanner scanner = new Scanner(System.in);
        int G1 = scanner.nextInt(); 
        int G2 = scanner.nextInt();
        int G3 = scanner.nextInt();
        int G4 = scanner.nextInt();

        int resp = G4 + G3;
        G1 -= G3;
        if (G1 < 0) G1 = 0;
        G2 += G1/2; G1 %= 2;
        resp += G2/2; G2 %= 2;
        if (G1 > 0 || G2 > 0) resp += 1;

        System.out.println(resp);
    }
}