//#pragma GCC optimize(2)
#include<bits/stdc++.h>
#include<unordered_map>
#include<unordered_set>
#define DEBUG
#define INF 0x3f3f3f3f3f3f3f3f
#define mod 1000000007
#define PI 3.14159265358979323846
#define Base 23333333
#define eps 0.000001
//#define set unordered_set
//#define map unordered_map
#define int long long
//#define LL long long
#define NO	cout<<"NO"<<endl
#define YES cout<<"YES"<<endl
#define No cout<<"No"<<endl
#define Yes cout<<"Yes"<<endl
#define mst(x) memset(x,0,sizeof(x))
#define debug(x) cout<<"DEBUG "<<#x<<" : "<<x<<endl

#define _up(x) ceil(x)
#define _down(x) floor(x)

#define range(x,y) 1

#define baoliu(x,y) cout<<fixed<<setprecision(y)<<x
//#define int unsigned long long
using namespace std;
//#define scanf scanf_s
//#define max(a,b) ((a) > (b) ? (a) : (b))
//#define min(a,b) ((a) < (b) ? (a) : (b))
inline int gcd(int a, int b) { return b > 0 ? gcd(b, a%b) : a; }
inline int lcm(int a, int b) { return a * b / gcd(a, b); }
inline int qpow(int a, int n) { int ans = 1;	while (n) { if (n & 1) { ans *= a; }a *= a; n >>= 1; }return ans; }
inline int _qpow(int a, int n) { int ans = 1; while (n) { if (n & 1) { ans *= a % mod;	ans %= mod; }a *= a; a %= mod; n >>= 1; }return ans % mod; }


/*
#define read() _read()
#define cout fout
#define cin fin
ifstream fin("in.txt");fstream fout("out.txt");
int _read() {	int tmp;	fin >> tmp;	return tmp;}
*/


inline int read() { int x = 0, f = 1;	char ch = getchar();	while (ch<'0' || ch>'9') { if (ch == '-') { f = -1; }		ch = getchar(); }	while (ch >= '0'&&ch <= '9') { x = 10 * x + ch - '0';		ch = getchar(); }	return x * f; }

const int maxnum = 1e5 + 5;
multiset<int>st[105];
int a[105][105];
signed main() {
	int T = read();
	while (T--) {
		int n = read(), m = read();
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= m; j++) {
				st[i].insert(read());
			}
		}
		for (int j = 1; j <= m; j++) {
			int id = -1, MIN = INF;
			for (int i = 1; i <= n; i++) {
				int res = *st[i].begin();
				if (res < MIN) {
					MIN = res;
					id = i;
				}
			}
			a[id][j] = MIN;
			st[id].erase(st[id].find(MIN));
			for (int i = 1; i <= n; i++) {
				if (i == id)continue;
				int res = *prev(st[i].end());
				a[i][j] = res;
				st[i].erase(prev(st[i].end()));
			}
		}
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= m; j++) {
				cout << a[i][j] << " ";
			}
			cout << endl;
		}
	}
	return 0;
}

