#include <cstdio>
#include <ctime>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <string>
#include <iostream>
#include <algorithm>
using namespace std;

#define getmid(l,r) ((l) + ((r) - (l)) / 2)
#define MEM(a,b) memset(a,b,sizeof(a))
#define MP(a,b) make_pair(a,b)
#define PB push_back

typedef long long ll;
typedef pair<int,int> pii;
const double eps = 1e-8;
const int INF = (1 << 30) - 1;
const int MAXN = 100010;
const ll mod = 1e9 + 7;

int T;
int N,M;
double dp[2010];
int pos[2010];

int main(){
    scanf("%d",&T);
    while(T--){
        memset(pos,0,sizeof(pos));
        scanf("%d%d",&N,&M);
        for(int i = 1; i <= M; ++i){
            int a;
            scanf("%d",&a);
            a++;
            pos[a] = 1;
        }
        memset(dp,0,sizeof(dp));
        for(int i = 1; i <= N; ++i){
            int p = i;
            for(; p >= 1; --p){
                if(pos[p]) break;
            }
            if(p == 1){
                dp[i] = log(1.0 * i);
            }
            //printf("%d %d\n",p,i);
            for(int j = p; j >= 1; --j){
                if(j < p && pos[j]) break;
                dp[i] = max(dp[i],dp[j - 1] + log(1.0 * (i - j + 1)));
            }
            //printf("%d %f\n",i,dp[i]);
        }
        ll ans = (ll)(1e6 * dp[N] / log(2.0));
        printf("%I64d\n",ans);
    }
    return 0;
}