[이코테] 정렬 알고리즘

 

 

 

n, k = map(int,input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
a.sort()
b.sort(reverse=True)

for i in range(k):
    if a[i] < b[i]:
        a[i],b[i] = b[i],a[i]
    else:
        break
print(sum(a))