#include <iostream>
#include <cstdint>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	
	uint32_t H, W, i, j;
	cin >> H >> W;
	vector<char> A(H * W);
	for (i = 0; i != H; ++i)
		for (j = 0; j != W; ++j)
			cin >> A[i * W + j];

	sort(A.begin(), A.end());
	for (i = 0; i != H; ++i)
	{
		cout << A[i * W];
		for (j = 1; j != W; ++j)
			cout << ' ' << A[i * W + j];
		cout << '\n';
	}

	return 0;
}