import bisect import copy import decimal import fractions import heapq import itertools import math import random import sys import time from collections import Counter,deque,defaultdict from functools import lru_cache,reduce from heapq import heappush,heappop,heapify,heappushpop,_heappop_max,_heapify_max def _heappush_max(heap,item): heap.append(item) heapq._siftdown_max(heap, 0, len(heap)-1) def _heappushpop_max(heap, item): if heap and item < heap[0]: item, heap[0] = heap[0], item heapq._siftup_max(heap, 0) return item from math import gcd as GCD read=sys.stdin.read readline=sys.stdin.readline readlines=sys.stdin.readlines write=sys.stdout.write A=list(map(int,readline().split())) B=list(map(int,readline().split())) C,D=map(int,readline().split()) w=min(C,A[1]) C-=w A[1]-=w B[1]+=w A[0]-=C B[0]+=C b=min(D,B[0]) D-=b B[0]-=b A[0]+=b B[1]-=D A[1]+=D ans=A[0] print(ans)