import java.util.*;

public class Exercise118{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    int[] a = new int[2];
    int[] b = new int[2];
    a[0] = sc.nextInt();
    a[1] = sc.nextInt();
    b[0] = sc.nextInt();
    b[1] = sc.nextInt();
    int f = sc.nextInt();
    int s = sc.nextInt();
    b[0] += Math.min((a[1] > f) ? 0 : f - a[1], a[0]);
    a[0] -= Math.min((a[1] > f) ? 0 : f - a[1], a[0]);
    a[0] += Math.min(s, b[0]);
    System.out.println(a[0]);
  }
}