import java.util.*;
import static java.lang.System.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		//入力
		Box A = new Box(sc.nextInt(),sc.nextInt());
		Box B = new Box(sc.nextInt(),sc.nextInt());
		int c = sc.nextInt();
		int d = sc.nextInt();
		
		//動作1
		if (c > A.black) {
			B.white += c - A.black;
			A.white -= c - A.black;
			B.black += A.black;
			A.black = 0;
			
		}
		else {
			B.black += c;
			A.black -= c;
		}
		
		//動作2
		if (d > B.white) {
			A.black += d - B.white;
			B.black -= d - B.white;
			A.white += B.white;
			B.white = 0;
		}
		else {
			A.white += d;
			B.white -= d;
		}
		
		//出力
		out.println(A.white);
	}
}

class Box {
	int white;
	int black;
	Box (int a, int b) {
		this.white = a;
		this.black = b;
	}
}