#include <bits/stdc++.h>
using namespace std;
namespace std {
template <class S, class T>
struct hash<pair<S, T>> {
  size_t operator()(const pair<S, T> &p) const {
    return ((size_t)1e9 + 7) * hash<S>()(p.first) + hash<T>()(p.second);
  }
};
template <class T>
struct hash<vector<T>> {
  size_t operator()(const vector<T> &v) const {
    size_t h = 0;
    for (auto i : v) h = h * ((size_t)1e9 + 7) + hash<T>()(i) + 1;
    return h;
  }
};
}  // namespace std
template <class T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "[ ";
  for (int i = 0; i < (int)v.size(); i++)
    os << v[i] << (i == v.size() - 1 ? " ]" : ", ");
  return os;
}
template <class T>
ostream &operator<<(ostream &os, const set<T> &v) {
  os << "{ ";
  for (const auto &i : v) os << i << ", ";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const map<T, U> &v) {
  os << "{";
  for (const auto &i : v) os << " " << i.first << ": " << i.second << ",";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
void dbgprint(const string &fmt) { cerr << endl; }
template <class H, class... T>
void dbgprint(const string &fmt, const H &h, const T &...r) {
  cerr << fmt.substr(0, fmt.find(",")) << "= " << h << " ";
  dbgprint(fmt.substr(fmt.find(",") + 1), r...);
}
const int inf = (int)1e9;
const double INF = 1e12, EPS = 1e-9;
int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  string t = s, ans = s;
  reverse((t).begin(), (t).end());
  t = s + t;
  for (int i = 0; i < (int)n; i++) {
    string u = t.substr(i, n);
    if (k == 1) {
      ans = min(ans, u);
      continue;
    }
    int len = 0;
    for (int j = n - 1; j >= 0 && u[j] == u[n - 1]; j--) len++;
    int len2 = min(n, len << min(k - 1, 13));
    string v = string(len2, u[n - 1]);
    for (int j = 0; j < (int)n - len2; j++) v += u[n - len - 1 - j];
    ans = min(ans, v);
  }
  cout << ans << endl;
  return 0;
}
