#include<iostream>
#include<cstring>

using namespace std;

const int N = 10010, M = 110, INF = 0x3f3f3f3f;

int f[M][M];
int a[N];
int n, m;

int main(){
    int T;
    cin >> T;
    
    while(T --){
        cin >> n >> m;
        
        for(int i = 1; i <= m; i ++) cin >> a[i];
        
        a[m + 1] = n + 1;
        
        // memset(f, 0x3f, sizeof f); 這句話區間dp暫時別用吧，初始條件估計還有別的

        
        for(int len = 1; len <= m; len ++)
            for(int l = 1; l + len - 1 <= m; l ++){
                int r = l + len - 1;
                if(len == 1) f[l][r] = a[r + 1] - a[l - 1] - 2;
                else{
                    f[l][r] = INF;
                    for(int k = l; k <= r; k ++)
                        f[l][r] = min(f[l][r], f[l][k - 1] + f[k + 1][r] + a[r + 1] - a[l - 1] - 2);
                }        
            }
        
        cout << f[1][m] << endl;
    }
    
    return 0;
}