#pragma GCC optimize("O3")
#pragma GCC target("tune=native")
#pragma GCC target("avx")
#include <algorithm>
#include <vector>
#include <iostream>
#include <numeric>
using ll = long long;
int main()
{
    int N, K;
    std::cin >> N >> K;
    std::vector<std::string> a(N);
    for (int i = 0; i < N; i++) { std::cin >> a[i]; }
    auto comp = [](const std::string& s1, const std::string& s2) { return s1 + s2 == s2 + s1 ? s1.size() > s2.size() : s1 + s2 > s2 + s1; };
    std::sort(a.begin(), a.end(), comp);
    std::vector<int> ind(N);
    std::iota(ind.begin(), ind.end(), 0);
    auto next = [&]() -> bool {
        std::string now;
        for (int i = 0; i < N; i++) { now += a[ind[i]]; }
        std::string max;
        std::vector<int> maxind;
        for (int i = N - 2, icnt = 0; i >= 0; i--) {
            if (ind[i] >= ind[i + 1]) { continue; }
            icnt++;
            for (int j = N - 1, jcnt = 0; j > i; j--) {
                if (ind[j] <= ind[i]) { continue; }
                jcnt++;
                std::swap(ind[i], ind[j]);
                std::reverse(ind.begin() + i + 1, ind.end());
                for (int j = N - 1; j > i; j--) {
                    std::swap(ind[i + 1], ind[j]);
                    std::string s;
                    for (int i = 0; i < N; i++) { s += a[ind[i]]; }
                    if (s < now and max < s) { max = s, maxind = ind; }
                    std::swap(ind[i + 1], ind[j]);
                }
                std::reverse(ind.begin() + i + 1, ind.end());
                std::swap(ind[i], ind[j]);
                if (jcnt > 20) { break; }
            }
            if (icnt > 20) { break; }
        }
        return ind = maxind, (max != "");
    };
    for (int i = 0; i < K; i++) {
        for (int i = 0; i < N; i++) { std::cout << a[ind[i]]; }
        std::cout << std::endl;
        if (not next()) { break; }
    }
    return 0;
}