#include <iostream>
#include <vector>
#include <map>
#include <algorithm>

using namespace std;

constexpr size_t MAX_M = 201, MAX_N = 1001;

vector<string> nums;
vector<bool> used;
map<size_t, int, greater<>> num_sizes;

string dp[MAX_M][MAX_N];

template <typename T>
void log_vector(const vector<T>& vec, const string& prefix = "") {
    clog << prefix << endl;
    for (const T& item : vec) {
        clog << item << " ";
    }
    clog << endl;
}


void output_from_used() {
    for (int i = 0; i < nums.size(); i++) {
        if (used[i]) { cout << nums[i]; }
    }
    cout << endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int nums_amount, target_size;
    cin >> target_size >> nums_amount;
    nums.resize(nums_amount), used.resize(nums_amount);
    for (int i = 0; i < nums_amount; i++) {
        cin >> nums[i];
    }
    sort(nums.begin(), nums.end(), [](const string& a, const string& b) {
        return a + b > b + a;
    });
    for (const string& num : nums) {
        num_sizes[num.size()]++;
    }
    log_vector(nums, "nums: ");
    // while (!can_form_combination(target_size, target_size)) {
    //     target_size--;
    // }
    clog << "target_size: " << target_size << endl;
    calc_used(target_size, target_size);
    log_vector(used, "used: ");
    output_from_used();

    return 0;
}