#include <bits/stdc++.h>

using namespace std;


typedef long long LL;

const long long LINF = (long long) 1e18;
const int INF = (int) 1e6;
const int MAX_SIZE = (int) 1e5 + 10;
long long A[MAX_SIZE], B[MAX_SIZE], temp[MAX_SIZE];
int N, K;


/**
*	Time complexity : O(N^3 * K^2) 
*/
long long solveFirstSubtask() {
	long long ans = -LINF;

	for (int i = 0; i < N; i++) {
		for (int j = 0; j < N; j++) {
			if (i == j) {
				// increase value
				for (int inc = 0; inc <= K; inc++) {
					for (int k = 0; k < N; k++) {
						temp[k] = A[k]; 
					}
					temp[i] += inc;
					long long res = 0;
					for (int k = 0; k < N; k++) {
						res += temp[k] * B[k];
					}
					ans = max(ans, res);
				}	
				// decrease value
				for (int dec = 0; dec <= K; dec++) {
					for (int k = 0; k < N; k++) {
						temp[k] = A[k]; 
					}
					temp[i] -= dec;
					long long res = 0;
					for (int k = 0; k < N; k++) {
						res += temp[k] * B[k];
					}
					ans = max(ans, res);
				}
			} else {
				for (int inc = 0; inc <= K; inc++) {
					for (int dec = 0; dec <= K - inc; dec++) {
						// increase i by k
						// and decrease j by K - k
						for (int k = 0; k < N; k++) {
							temp[k] = A[k]; 
						}
						temp[i] += inc;
						temp[j] -= dec;
						long long res = 0;
						for (int k = 0; k < N; k++) {
							res += temp[k] * B[k];
						}
						ans = max(ans, res);
					}
				}
			}
		}	
	}

	return ans;
}


/**
*	O(N * N)	
*/
long long solveSecondSubtask() {
	long long ans = -LINF;
	
	for (int i = 0; i < N; i++) {
		{
			// inc i by K
			long long temp = 0;
			for (int j = 0; j < N; j++) {
				temp += A[j] * B[j];
				if (j == i) {
					temp += B[j] * K;
				}
			}
			ans = max(ans, temp);
		}
		{
			// dec i by K
			long long temp = 0;
			for (int j = 0; j < N; j++) {
				temp += A[j] * B[j];
				if (j == i) {
					temp -= B[j] * K;
				}
			}
			ans = max(ans, temp);
		}
	}

	return ans;
}

/**
*	O(N log N)
*/
long long solveThirdSubtask() {
	long long sum = 0;
	for (int i = 0; i < N; i++) {
		sum += A[i] * B[i];
	}

	//cout << "sum " << sum << endl;

	sort(B, B + N);
	long long val = max(abs(B[0]), abs(B[N - 1]));
	long long ans = sum + val * K;
	
	return ans;
}


int MAXN, MAXK, MAXA, MAXT; 
int subtaskToSolve = 1;

long long solveSubask() {
	switch (subtaskToSolve) {
		case 1 : return solveFirstSubtask(); 
		case 2 : return solveSecondSubtask(); 
		case 3 : return solveThirdSubtask();
	} 	
}

void readInput() {
	switch (subtaskToSolve) {
		case 1:
			MAXN = MAXK = MAXA = 10;
			break;
		case 2:
			MAXN = MAXK = MAXA = 1000;
			MAXK = (int) 1e5;
			break;
		case 3:
			MAXN = MAXA = 100000;
			MAXK = (int) 1e9;
			break;
	}
	
	scanf("%d %d", &N, &K);
	assert(N >= 1 && N <= MAXN);
	assert(K >= 0 && K <= MAXK);
	
	for (int i = 0; i < N; i++) {
		scanf("%lld", &A[i]);
		assert(A[i] >= -MAXA && A[i] <= MAXA);
	}
	
	for (int i = 0; i < N; i++) {
		scanf("%lld", &B[i]);
		assert(B[i] >= -MAXA && B[i] <= MAXA);
	}
}


void generateRandomInput() {
	subtaskToSolve = 2;
	
	switch (subtaskToSolve) {
		case 1:
			MAXN = MAXK = MAXA = 10;
			break;
		case 2:
			MAXN = MAXK = 1000;
			MAXA = (int) 1e5;
			break;
		case 3:
			MAXN = MAXA = 100000;
			MAXK = (int) 1e9;
			break;
	}

	N = rand() % MAXN + 1;
	K = rand() % MAXK;

	for (int i = 0; i < N; i++) {
		int temp = rand() % MAXA;
		if (rand() % 2 == 0) {
			temp *= -1;
		}

		A[i] = temp;
	}

	for (int i = 0; i < N; i++) {
		int temp = rand() % MAXA;
		if (rand() % 2 == 0) {
			temp *= -1;
		}

		B[i] = temp;
	}
}

void print() {
	cout << N << " " << K << endl;

	for (int i = 0; i < N; i++) {
		cout << A[i] << " ";
	}
	cout << endl;

	for (int i = 0; i < N; i++) {
		cout << B[i] << " ";
	}
	cout << endl;
}

int main() {
	int T = 100000;
	scanf("%d", &T);
	assert(T >= 1 && T <= 10);
	int tc = 0;

	while (T--) {
		subtaskToSolve = 3;
		
		readInput();
		//generateRandomInput();
		//cout << endl;
		//print();
		
		/*
		subtaskToSolve = 1;
		long long ans = solveSubask();
		print();
		*/
		
		//subtaskToSolve = 2;
		//long long bans = solveSubask();
		//print();

		long long ans = solveSubask();
		cout << ans << endl;
		//print();
		
		/*
		cout << endl << "test case " << tc++ << endl;
		cout << bans << " " << bbans << endl;
		assert(bans == bbans);
		*/
	}
	
	return 0;
}