# Whats wrong in the following code? CHFIMPRS

#include<bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define forn(i,a,b) for(int i =a;i<b;i++)
#define fi first
#define se second
#define fast ios_base::sync_with_stdio(false);
using namespace std;

typedef long long int ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

void solve(){
int n,m;
cin >> n >>m;
int grid[n][m];
map<int,int > count;
forn(i,0,n){
forn(j,0,m){
cin >> grid[i][j];
count[grid[i][j]]++;
}
}
set<int> centre;
set<int> anywhere;
for(auto e:count){
if(e.second >= 2)
anywhere.insert(e.first);
else{
centre.insert(e.first);
// anywhere.insert(e.first);
}
}
// if(m%2==0){
// 	if(centre.size()>0){
// 		cout << "-1" <<  endl;return;
// 	}
// }

int ans[n][m];
memset(ans,0,sizeof(ans));

forn(i,0,n){
forn(j,0,m/2){
if(anywhere.size()==0){
// cout << i << endl;
cout << -1 << endl;return;
}
int val = *anywhere.begin();
ans[i][j] = *anywhere.begin();
ans[i][m-1-j] = val;
// cout << i << " " << j << " " << (m-1) << " " ;
count[val]-=2;
if(count[val]<2){
anywhere.erase(val);
if(count[val]==1)
centre.insert(val);
}
}
// cout << endl;

if(m&1){
if(centre.size()!=0){
int valc = *centre.begin();
ans[i][m/2] = valc;
count[valc]--;
if(count[valc]==0)
centre.erase(valc);
}
else{
if(anywhere.size()==0){
// cout << i << endl;
//
cout << -1 << endl;return;
}
int valc = *anywhere.begin();
ans[i][m/2] = valc;
count[valc]--;
if(count[valc]==1)
{
anywhere.erase(valc);
centre.insert(valc);
}
if(count[valc]==0)
anywhere.erase(valc);
}
}
}
forn(i,0,n){
forn(j,0,m)
cout << ans[i][j] << " ";
cout << endl;
}
}

int main(){
fast;
#ifndef ONLINE_JUDGE
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
#endif

int t;cin >> t;while(t--)
solve();
}

was getting WA