#include <cstdio>
#include <algorithm>
#include <vector>
#include <limits.h>

using namespace std;

typedef long long ll;

struct DATA{
    ll pos;
    ll group;
    ll self_idx, other_idx;
    DATA(){}
    bool operator<(const DATA& target)const{
        return pos<target.pos;
    }
};
vector<DATA> input;
ll T;

int main()
{
    scanf("%lld", &T);
    while(T--){
        ll N, M;
        scanf("%lld%lld", &N, &M);

        input = vector<DATA>(N+M+1);

        for(int i=1;i<=N;i++){
            scanf("%lld", &input[i].pos);
            input[i].group = -1;
        }
        // A그룹 입력

        for(int i=(int)(N+1);i<=M+N;i++){
            scanf("%lld", &input[i].pos);
            input[i].group = 1;
        }
        // B그룹 입력

        sort(input.begin()+1, input.end());
        // 정렬

        vector<ll> asum, rasum, bsum, rbsum;
        asum = vector<ll>(N+M+2);
        rasum = vector<ll>(N+M+2);
        bsum = vector<ll>(N+M+2);
        rbsum = vector<ll>(N+M+2);
        // 누적합 배열 선언

        int aidx=0, bidx=0;
        for(int i=1;i<=N+M;i++){
            if(input[i].group==-1){
                input[i].self_idx=++aidx;
                input[i].other_idx=bidx;
            }else{
                input[i].self_idx=++bidx;
                input[i].other_idx=aidx;
            }
        }
        // 전체 배열에서 상대 인덱스 저장

        for(int i=1;i<=N+M;i++){
            asum[i] = asum[i-1];
            bsum[i] = bsum[i-1];
            if(input[i].group == -1){
                asum[i] += input[i].pos;
            }else{
                bsum[i] += input[i].pos;
            }
        }

        for(int i=(int)(N+M);i>=1;i--){
            rasum[i] = rasum[i+1];
            rbsum[i] = rbsum[i+1];
            if(input[i].group == -1){
                rasum[i] += input[i].pos;
            }else{
                rbsum[i] += input[i].pos;
            }
        }
        // 누적합

        ll min_idx=0;
        ll min_val = LONG_LONG_MAX;
        for(int i=1;i<=N+M;i++){

            ll resa = 0, resb = 0;
            if(input[i].group == -1){
                if(i>1){
                    resa += llabs(asum[i-1]-input[i].pos*(input[i].self_idx-1));
                    resb += llabs(bsum[i-1]-input[i].pos*(input[i].other_idx));
                }
                if(i<N+M){
                    resa += llabs(rasum[i+1]-input[i].pos*(N-input[i].self_idx));
                    resb += llabs(rbsum[i+1]-input[i].pos*(M-input[i].other_idx));
                }
            }else{
                if(i>1){
                    resa += llabs(asum[i-1]-input[i].pos*(input[i].other_idx));
                    resb += llabs(bsum[i-1]-input[i].pos*(input[i].self_idx-1));
                }
                if(i<N+M){
                    resa += llabs(rasum[i+1]-input[i].pos*(N-input[i].other_idx));
                    resb += llabs(rbsum[i+1]-input[i].pos*(M-input[i].self_idx));
                }
            }
            ll res = resa*M+resb*N;
//                    printf("i:%d val:%d %lld\n", i, input[i].pos, res);
            if(res<min_val){
                min_idx = i;
                min_val = res;
            }
        }
        // 누적합 배열 이용해서 한 정점에서 다른 모든 정점까지의 거리의 합 계산

        printf("%lld.0\n", input[min_idx].pos);
    }
    return 0;
}

// 3 2 2 7 12 5 8