#define _USE_MATH_DEFINES

#include <iostream>	//cin, cout
#include <vector>	//vector
#include <algorithm> //sort,min,max,count
#include <string>	//string,getline, to_string
#include <ios>		//fixed
#include <iomanip>	//setprecision
#include <utility> //swap, pair
#include <cstdlib>	//abs(int)
#include <cmath>	//sqrt,ceil,M_PI, pow, sin
#include <sstream>	//stringstream,getline
#include <numeric>	//gcd, accumlate
#include <deque>	//deque
#include <random>	//randam_device
#include <limits>	//numeric_limits

using namespace std;
constexpr long long int D_MOD = 1000000007;

int main() {

	int H, W;
	cin >> H >> W;

	vector<int> A(H * W);

	for (int i = 0; i < H * W; i++) {
		cin >> A[i];
	}

	sort(A.begin(), A.end());

	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W - 1; j++) {
			cout << A[W * i + j] << " ";
		}
		cout << A[W * i + W - 1] << endl;
	}

	return 0;

}