#include <bits/stdc++.h>   using namespace std;   mt19937 prng(chrono::steady_clock::now().time_since_epoch().count());   void testCase(int caseno) {     int n, k, a, b;     cin >> n >> k;     multiset<int> aa;     multiset<int> bb;     int sum = 0;     for (int i = 0; i < n; i++) {       cin >> a;       sum += a;       aa.insert(a);     }     for (int i = 0; i < n; i++) {       cin >> b;       bb.insert(b);     }     for (int i : aa) {     }     for (int i : bb) {     }     int it = 0;     while (*(aa.begin()) < *(--bb.end()) && it < k) {       it++;       sum -= *(aa.begin());       sum += *(--bb.end());       aa.insert(*(--bb.end()));       bb.insert(*(aa.begin()));       auto ita = aa.begin();       auto itb = --bb.end();       aa.erase(ita);       bb.erase(itb);     }     cout << sum << endl;   }   int main() {     int t;     cin >> t;     for (int i = 0; i < t; i++) {       testCase(i + 1);     }     return 0;   }   