// @author godmar
import java.util.*;
import static java.lang.Math.*;

public class godmar
{
    public static void main(String ...args) {
        var sc = new Scanner(System.in);
        int r = sc.nextInt();
        int g = sc.nextInt();
        int b = sc.nextInt();
        int cr = sc.nextInt();
        int cg = sc.nextInt();
        int cb = sc.nextInt();
        int crg = sc.nextInt();
        int cgb = sc.nextInt();
        int need_r = max(r - cr, 0);
        int need_b = max(b - cb, 0);
        int need_g = max(g - cg, 0);
        if (need_r > crg || need_b > cgb) {
            System.out.println(-1);
            return;
        }
        crg -= need_r;
        cgb -= need_b;
        if (need_g > cgb + crg) {
            System.out.println(-1);
            return;
        }
        System.out.println(need_r + need_g + need_b);
    }
}