using System;
using System.Collections.Generic;
using System.Linq;

class Magatro
{
    static void Main()
    {
        int Aw, Ab;
        int Bw, Bb;
        int C, D;
        string[] s = Console.ReadLine().Split(' ');
        Aw = int.Parse(s[0]);
        Ab = int.Parse(s[1]);
        s = Console.ReadLine().Split(' ');
        Bw = int.Parse(s[0]);
        Bb = int.Parse(s[1]);
        s = Console.ReadLine().Split(' ');
        C = int.Parse(s[0]);
        D = int.Parse(s[1]);
        if (Ab >= C)
        {
            Ab -= C;
        }
        else
        {
            Aw -= C - Ab;
            Bw += C - Ab;
        }
        Aw += Math.Min(D, Bw);
        Console.WriteLine(Aw);            
    }
}