#include <bits/stdc++.h>
using namespace std;
using Int = long long;
template <typename T1, typename T2>
inline void chmin(T1 &a, T2 b) {
  if (a > b) a = b;
}
template <typename T1, typename T2>
inline void chmax(T1 &a, T2 b) {
  if (a < b) a = b;
}
Int n, k;
string calc(string s) {
  reverse(s.begin(), s.end());
  Int cnt = 0;
  while (cnt < n && s[0] == s[cnt]) cnt++;
  Int len = cnt << k;
  if (len >= n) return string(n, s[0]);
  string res;
  for (Int i = cnt; i < n; i++)
    if (len + (Int)res.size() < n) res += s[i];
  return string(len, s[0]) + res;
}
signed main() {
  string s;
  cin >> n >> k >> s;
  chmin(k, 20);
  k--;
  string ans = s;
  string t(s);
  reverse(t.begin(), t.end());
  string b = s + t;
  for (Int i = 0; i <= n; i++) {
    string c = b.substr(i, n);
    chmin(ans, calc(c));
  }
  cout << ans << endl;
  return 0;
}
