class Bag {
	int white;
	int black;

	Bag(int x, int y) {
		this.white = x;
		this.black = y;
	}
}

public class No_149 {

	public static void main(String[] args) {
		java.util.Scanner sc = new java.util.Scanner(System.in);
		Bag A = new Bag(sc.nextInt(), sc.nextInt());
		Bag B = new Bag(sc.nextInt(), sc.nextInt());
		int select1 = sc.nextInt();
		int select2 = sc.nextInt();

		if (A.black < select1) {
			select1 -= A.black;
			B.black += A.black;
			A.black = 0;
			B.white += select1;
			A.white -= select1;
		} else {
			A.black -= select1;
			B.black += select1;
		}

		if (B.white < select2) {
			select2 -= B.white;
			A.white += B.white;
			B.white = 0;
			A.black += select2;
			B.black -= select2;
		} else {
			B.white -= select2;
			A.white += select2;
		}
		System.out.println(A.white);
		sc.close();

	}

}