#include<bits/stdc++.h>

 using namespace std;

 typedef long long ll;

 typedef unsigned int uint;

 typedef unsigned long long ull;

 typedef pair<int,int> PII;

 typedef pair<ll,ll> Pll;

 typedef vector<int> VI;

 typedef vector<PII> VII;

 #define N  310000

 #define M  4100000

 #define fi first

 #define se second

 #define MP make_pair

 #define pi acos(-1)

 #define mem(a,b) memset(a,b,sizeof(a))

 #define rep(i,a,b) for(int i=(int)a;i<=(int)b;i++)

 #define per(i,a,b) for(int i=(int)a;i>=(int)b;i--)

 #define lowbit(x) x&(-x)

 #define Rand (rand()*(1<<16)+rand())

 #define id(x) ((x)<=B?(x):m-n/(x)+1)

 #define ls p<<1

 #define rs p<<1|1

 const ll MOD=1e9+,inv2=(MOD+)/;

       double eps=1e-;

       int INF=1e9;

       int da[]={-,,,};

       int db[]={,,-,};

       int vis[][],a[N],b[],n;

 int read()

 {

    int v=,f=;

    char c=getchar();

    while(c<||<c) {if(c=='-') f=-; c=getchar();}

    while(<=c&&c<=) v=(v<<)+v+v+c-,c=getchar();

    return v*f;

 }

 int isok()

 {

     mem(vis,);

     int m=b[]+b[]*+b[]*;

     rep(i,,b[]) vis[][i]=;

     rep(i,,b[])

      rep(j,,m)

       if(vis[][j]) vis[][j+i*]=;

     rep(i,,b[])

      rep(j,,m)

       if(vis[][j]) vis[][j+i*]=;

     int ans=;

     rep(i,,n)

     {

         int t=INF;

         rep(j,,m)

          if(vis[][j]&&(a[i]-j*)%==) t=min(t,(a[i]-j*)/);

         if(t==INF) return -;

         ans=max(ans,t);

     }

     return ans;

 }

 int main()

 {

     //freopen("1.in","r",stdin);

     //freopen("1.out","w",stdout);

     int cas;

     scanf("%d",&cas);

     while(cas--)

     {

         n=read();

         rep(i,,n) a[i]=read();

         int ans=INF;

         for(b[]=;b[]<=;b[]++)

          for(b[]=;b[]<=;b[]++)

           for(b[]=;b[]<=;b[]++)

           {

               int t=isok();

               if(t!=-) ans=min(ans,b[]+b[]+b[]+t);

           }

         if(ans==INF) printf("-1\n");

          else printf("%d\n",ans);

     }

     return ;

 }