#include <iostream>
#include <iomanip>
#include <cstdio>
#include <vector>
#include <string>
#include <algorithm>
#include <map>
#include <set>
 
using namespace std;
typedef long long ll;

int N, K;
string S;

string cv;

int main()
{
    ios_base::sync_with_stdio(0);
    
    cin >> N >> K >> S;
    for (int i = N - 1; i >= 0; i--)
        S += S[i];

    cv = S.substr(0, N);
    for (int i = 1; i <= N; i++)
        cv = min (cv, S.substr(i, N));
    if (K == 1)
    {
        cout << cv << "\n";
        return 0;
    }

    K--;
    //cout << cv << endl;
    int na = 1;
    while (na < N && cv[na] == cv[na-1])
        na++;

    int ntot = na;
    for (int i = 0; i < K; i++)
    {
        ntot = min (N, ntot * 2);
        if (ntot == N) break;
    }

    for (int i = 0; i < ntot; i++)
        cout << cv[0];
    for (int i = 0; i < N - ntot; i++)
        cout << cv[i+na];
    cout << "\n";
}