a.txt

#include<bits/stdc++.h>
typedef long long ll;
typedef long double ld;
#define FASTIO ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
  
using namespace std;
 
const ll inf = 1e17;
const ll N = 1e6+10;
const ll bits = 30;
const ll mod = 1e9+7;


int main(){
    // FASTIO;

    ll q,h,n;

    cin>>q;

    while(q--){
        cin>>h>>n;
        cout<<h<<" "<<n<<"\n";
        vector<ll>arr(n);
        
        for(int i=0;i<n;i++){
            cin>>arr[i];
        }
        cout<<"here";

        arr.push_back(0);


        ll ans = 0;

        for(int i=0;i<n;i++){
            if(arr[i]-arr[i+1]>2){
                ans+=arr[i]-arr[i+1]-2;
            }
        }

        cout<<ans<<"\n";
    }

    


    
}