import sequtils, strutils, math

var
    a = readLine(stdin).split.map(parseInt)
    b = readLine(stdin).split.map(parseInt)
    c,d:int
(c, d) = readLine(stdin).split.map(parseInt)

if d > b[0]:
    b[0] += min(a[0], c)
    a[0] -= min(a[0], c)
else:
    if a[1] < c:
        a[0] -= (c - a[1])

echo a[0] + min(d, b[0])