a = [int(x) for x in input().split(',')]
b = [int(x) for x in input().split(',')]
c = int(input())

t = list(zip(a, b))
t.sort()

for i in range(len(t)):
    if t[i][0] > c:
        break
    if t[i][0] >= t[i][1]:
        continue
    c += t[i][1] - t[i][0]
print(c)