#include<bits/stdc++.h>

using namespace std;

typedef long long ll;

typedef pair<ll,ll> pll;

const int N=2e5+10;

ll a[N];

signed main(){

   ios::sync_with_stdio(false);

   cin.tie(0);cout.tie(0);

   ll t;cin>>t;

   while(t--){

      ll n,m;cin>>n>>m;

      vector<ll> sum(n+1,0);

      for(ll i=1;i<=m;i++){

         ll p;cin>>p;sum[p]++;

      }

      ll l=1,r=1e9;

      while(l<r){

         ll mid=l+r>>1;

         ll p=0,q=0;

         for(ll i=1;i<=n;i++){

            if(mid<sum[i]) p+=sum[i]-mid;//需要几个人代替

            else if(mid>=sum[i]) q+=(mid-sum[i])/2;//把不适合的人顶替上

         }

         if(q>=p){

            r=mid;

         }

         else l=mid+1;

      }

      cout<<l<<endl;

   }

}