#include <bits/stdc++.h>
//#include <boost/multiprecision/cpp_int.hpp>
//#define ll cpp_int
#define ll long long
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define fi(a, b, c, d) for (int a = b; a < c; a += d)
#define fl(a, b, c, d) for (ll a = b; a < c; a += d)
#define fei(a, b, c, d) for (int a = b; a <= c; a += d)
#define fel(a, b, c, d) for (ll a = b; a <= c; a += d)
#define all(x) (x).begin(), (x).end()
#define vi vector<int>
#define vll vector<ll>
#define viip vector<pair<int, int>>
#define vllp vector<pair<ll, ll>>
#define pb push_back
//pairs
#define pi pair<int, int>
#define pll pair<ll, ll>
#define mp make_pair
#define F first
#define S second
#define mod 1000000007
//using boost::multiprecision::cpp_int;
using namespace std;
bool iseven(ll n)
{
    if (n % 2 == 0)
        return true;
    else
    {
        return false;
    }
}
ll position(ll a)
{
    vector<ll> p(30, 0);
    //unordered_set<ll>s;
    ll s = 0;
    long double x = a;
    int i = 0;
    while (a > 0)
    {
        if ((a & 1) == 1)
        {
            // s.insert(i);
            s++;
        }

        a = a >> 1;
        i++;
    }

    return s;
}
ll power(ll x, unsigned ll y)
{
    ll res = 1; // Initialize result

    while (y > 0)
    {
        // If y is odd, multiply x with result
        if (y & 1)
            res = res * x;

        // y must be even now
        y = y >> 1; // y = y/2
        x = x * x;  // Change x to x^2
    }
    return res;
}
void print(vector<ll> a, ll n)
{
    for (int i = 0; i < n; i++)
        cout << a[i] << " ";
    cout << "\n";
}
bool sec(const pair<ll, ll> &a, const pair<ll, ll> &b)
{
    /*if (a.first == b.first)
        return (a.second > b.second);
    else*/
    // {
    return (a.first >= b.first);
    //}
}
vector<ll> suffix(vll &a, ll n)
{
    vll pre(n, 0);
    pre[n - 1] = a[n - 1];
    for (int i = n - 2; i >= 0; i--)
    {
        pre[i] = pre[i + 1] ^ a[i];
    }
    return pre;
}
vector<ll> preffix(vll &a, ll n)
{
    vll pre(n, 0);
    pre[0] = a[0];
    for (int i = 1; i < n; i++)
    {
        pre[i] = pre[i - 1] ^ a[i];
    }
    return pre;
}
unordered_set<ll> primeFactors(ll n)
{
    // Print the number of 2s that divide n
    unordered_set<ll> s;
    while (n % 2 == 0)
    {
        s.insert(2);
        n = n / 2;
    }

    // n must be odd at this point. So we can skip
    // one element (Note i = i +2)
    for (ll i = 3; i <= sqrt(n); i = i + 2)
    {
        // While i divides n, print i and divide n
        while (n % i == 0)
        {
            s.insert(i);
            n = n / i;
        }
    }

    // This condition is to handle the case when n
    // is a prime number greater than 2
    if (n > 2)
        s.insert(n);
    return s;
}

vll primeArray;
void SieveOfEratosthenes(ll n)
{
    // Create a boolean array "prime[0..n]" and initialize
    // all entries it as true. A value in prime[i] will
    // finally be false if i is Not a prime, else true.
    vector<bool> prime(n + 1, true);

    for (ll p = 2; p * p <= n; p++)
    {
        // If prime[p] is not changed, then it is a prime
        if (prime[p] == true)
        {
            // Update all multiples of p greater than or
            // equal to the square of it
            // numbers which are multiple of p and are
            // less than p^2 are already been marked.
            for (ll i = p * p; i <= n; i += p)
                prime[i] = false;
        }
    }

    // Print all prime numbers54

    //primeArray.pb(1);
    for (ll i = 2; i <= n; i++)
    {
        if (prime[i])
        {
            primeArray.pb(i);
        }
    }
}

void solve()
{
    ll n, m;
    cin >> n >> m;
    ll a[n][m];
    vllp v;
    rep(i, n)
    {
        rep(j, m)
        {
            cin >> a[i][j];
            v.pb({a[i][j], i});
        }
    }
    sort(all(v));
    ll i = 0;
    set<pair<ll, ll>> s;
    fl(k, 0, m, 1)
    {
        ll c = v[k].F;
        ll r = v[k].S;
        rep(j, m)
        {
            if (a[r][j] == c && s.find({r, j}) == s.end())
            {
                swap(a[r][j], a[r][i]);
                s.insert({r, i});
                i++;
                break;
            }
        }
    }
    rep(i, n)
    {
        rep(j, m)
        {
            cout << a[i][j] << " ";
        }
        cout << "\n";
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ll t = 1;
    cin >> t;
    // SieveOfEratosthenes(1000000);

    while (t--)
    {
        solve();
    }

    return 0;
}