/*
 * PRATA.cpp
 *
 *  Created on: Jun 22, 2014
 *      Author: Arpit Bhayani
 */

#include <queue>
#include <cstdio>
#include <cstdlib>
#include <iostream>

using namespace std;

#define DEBUG 0
#define gc getchar
#define ll long long

void scanint(ll int &x) {
    register ll int c = gc();
    x = 0;
    for (; (c < 48 || c > 57); c = gc())
        ;
    for (; c > 47 && c < 58; c = gc()) {
        x = (x << 1) + (x << 3) + c - 48;
    }
}

int readline(char * str) {

    int i = 0;
    char ch;
    while ((ch = getchar()) != '\n') {
        str[i++] = ch;
    }
    str[i] = '\0';
    return i;
}

int rank[51];
int mult[51];

int main(int argc, char * argv[]) {

    int t;
    int array[51];

    scanf("%d", &t);
    while (t--) {

        priority_queue<int, std::vector<int>, std::greater<int> > q;
        int count = 0;
        int p, l;

        scanf("%d%d", &p, &l);

        for (int i = 0; i < l; i++) {
            scanf("%d", &rank[i]);
            array[i] = rank[i];
            mult[i] = 1;

            q.push(rank[i]);
        }

        int time = 0;

        while (1) {
            //cout << "IN LOOP : count " << count << " and p = " << p << endl;

            time = q.top();
            q.pop();

            while (!q.empty() && q.top() == time)
                q.pop();

            for (int i = 0; i < l; i++) {
                if (array[i] == time) {
                    count++;
                    mult[i]++;
                    array[i] = array[i] + rank[i] * mult[i];
                    q.push(array[i]);
                }
            }

            if (count >= p)
                break;

        }

        printf("%d\n", time);

    }
    return 0;
}