#include <bits/stdc++.h>
using namespace std;
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--;
  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, na * 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";
}
