#define LOCAL
#include<bits/stdc++.h>
#include<unistd.h>
#include<bits/extc++.h>
//#define getchar my_gechar
#define ll long long
#define lll __int128
#define db double
#define ldb long double
#define pb emplace_back
#define fi first
#define se second
#define mp make_pair
#define pii pair<int,int> 
#define vec Point
#define fill0(a) memset(a,0,sizeof(a))
#define fill1(a) memset(a,-1,sizeof(a))
#define fillbig(a) memset(a,63,sizeof(a))
// #define max(a,b) ((a)<(b)?(b):(a))
// #define min(a,b) ((a)<(b)?(a):(b))
#define vi vector<int> 
#define vl vector<ll>
#define lowbit(x) (x)&(-x)
//#define sort stable_sort
using namespace std;
using namespace __gnu_pbds;
char buffer[32769];
unsigned li = 0;
inline char my_gechar(){
    if(buffer[li] == '\0') buffer[read(0, buffer, 32768)] = '\0',li = 0;
    return buffer[li++];
}
namespace ly
{
    namespace IO
    {
        #ifndef LOCAL
            constexpr auto maxn=1<<20;
            char in[maxn],out[maxn],*p1=in,*p2=in,*p3=out;

            #define flush() (fwrite(out,1,p3-out,stdout))
            #define putchar(x) (p3==out+maxn&&(flush(),p3=out),*p3++=(x))
            class Flush{public:~Flush(){flush();}}_;
        #endif
        namespace usr
        {
            template<typename type>
                  inline type read(type &x)
            {
                x=0;bool flag(0);char ch=getchar();
                while(!isdigit(ch)) flag^=ch=='-',ch=getchar();
                while(isdigit(ch)) x=(x<<1)+(x<<3)+(ch^48),ch=getchar();
                return flag?x=-x:x;
            }
            template<typename type>
            inline void write(type x)
            {
                x<0?x=-x,putchar('-'):0;
                static short Stack[50],top(0);
                do Stack[++top]=x%10,x/=10;while(x);
                while(top) putchar(Stack[top--]|48);
            }
            inline int read(double &x){return scanf("%lf",&x);}
            inline int read(long double &x){return scanf("%Lf",&x);}
            inline void dwrite(const double &x,int y=6,bool flag=1){printf("%.*lf",y,x),flag?putchar(' '):putchar(' ');}
            inline void dwrite(const long double &x,int y=6,bool flag=1){printf("%.*Lf",y,x),flag?putchar(' '):putchar(' ');}
            inline char read(char &x){do x=getchar();while(isspace(x));return x;}
            inline char write(const char &x){return putchar(x);}
            inline void read(char *x){static char ch;read(ch);do *(x++)=ch;while(!isspace(ch=getchar())&&~ch);}
            inline void write(const char *x){while(*x)putchar(*(x++));}
            inline void read(string &x){char ch[1000005]={};read(ch),x=ch;}
            inline void write(const string &x){int len=x.length();for(int i=0;i<len;++i)putchar(x[i]);}
            template<typename type,typename...T>
            inline void read(type &x,T&...y){read(x),read(y...);}
            template<typename type,typename...T>
            inline void write(const type &x,const T&...y){write(x),putchar(' '),write(y...),sizeof...(y)^1?0:putchar(' ');}
            inline __int128 read(){static __int128 x;return read(x);}
            template<typename type>
            inline type put(type x,bool flag=1){write(x),flag?putchar(' '):putchar(' ');return x;}
        }
        #ifndef LOCAL
            #undef getchar
            #undef flush
            #undef putchar
        #endif
    }using namespace IO::usr;
}using namespace ly::IO::usr;
struct Point{
    int x,y;
    Point operator +(const Point& b)const{return {x+b.x,y+b.y};}
    Point operator -(const Point& b)const{return {x-b.x,y-b.y};}
    bool operator <(const Point& b)const{
        if(x!=b.x)return x<b.x;
        return y<b.y;
    }
};
const int N=1e5+5;
const int M=1e6+5;
const int inf=1e9+5;
const int mod=1e9+7;
const int bit=50;
//mt19937 sj(chrono::steady_clock::now().time_since_epoch().count());
int B=705;
bitset<10005> b[10005];
int n;
int a[N];
unordered_map<int,int> m,m1,m2;
inline bool cmp(int a,int b){
    if(m[a]==m[b]) return a<b;
    return m[a]>m[b];
}
int cnt;
bool vis[10005];
inline void solve(){
    read(n);
    m.clear();
    m1.clear();
    m2.clear();
    cnt=0;
    fill0(vis);
    for(int i=1;i<=n;++i) b[i].reset();
    bool flag=n&1;
    flag=n&1;
    for(int i=1;i<=n;++i){
        read(a[i]);
        if(!m1.count(a[i])) m1[a[i]]=++cnt,m2[cnt]=a[i];
        a[i]=m1[a[i]];
        m[a[i]]++;
        if(m[a[i]]>n/2) flag=1;
        //cout<<a[i]<<' '<<m[a[i]]<<' '<<i<<' '<<flag<<endl;
    }

    
    if(flag||n%2==1){
        cout<<-1<<endl;
        return;
    }
    sort(a+1,a+n+1,cmp);
    for(int i=1;i<=n/2;++i){
        b[i][a[i]]=1;
        b[i][a[i+n/2]]=1;
    }
    int ans=n/2;
    for(int i=1;i<=n/2;++i){
        if(vis[i]) continue;
        for(int j=1;j<=n/2;++j){
            if(vis[j]) continue;
            if((b[i]&b[j]).count()==0){
                vis[j]=1;
                --ans;
                if((b[i]&b[j]).count()!=0) while(1);
                b[i]|=b[j];
                if(b[i].count()%2!=0) while(1);
            }
        }
    }
    cout<<ans<<endl;
    int sum=0;
    int num=0;
    for(int i=1;i<=n/2;++i){
        if(vis[i]) continue;
        write(b[i].count());
        cout<<' ';
        ++num;
        sum+=b[i].count();
        for(int j=1;j<=n;++j){
            if(b[i][j]) write(m2[j]),cout<<' ';
        }
        cout<<endl;
    }

}

signed main()
{   
    int _=1;
    read(_);
    while(_--) solve();
    return (0-0);
}