n, k = map(int, input().split())
ans = sum(map(int, input().split()))
b = map(int, input().split())
c = map(int, input().split())
d = []
for bi, ci in zip(b, c):
    ans += ci
    d.append(bi - ci)
ans += sum(sorted(d, reverse=True)[:k])
print(ans)