#include <bits/stdc++.h>
using namespace std;
int n, k, pos[100];
string s;
int main() {
  cin >> n >> k >> s;
  pos[0] = -1;
  int j = -1;
  for (int i = 1; i < n; i++) {
    while (j > -1 && s[i] != s[j + 1]) j = pos[j];
    if (s[i] == s[j + 1]) j++;
    pos[i] = j;
  }
  cout << s;
  string t;
  for (int i = pos[n - 1] + 1; i < n; i++) t += s[i];
  for (int i = 2; i <= k; i++) cout << t;
  cout << endl;
  return 0;
}
