// #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
int main() {
    // Input
    int H, W;
    cin >> H >> W;
    vector<int> A(H * W);
    rep(i, H * W) cin >> A[i];

    // Output
    sort(A.begin(), A.end());
    vector<vector<int>> B(H, vector<int>(W));
    rep(i, H) rep(j, W) B[i][j] = A[i * W + j];
    rep(i, H) {
        rep(j, W) {
            if (j) cout << ' ';
            cout << B[i][j];
        }
        cout << '\n';
    }
}