#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int N, K;
string S, T;
int A[202020], pos = 0;

int main() {
  cin >> N >> K;
  cin >> S;
  for (int i = K; i <= N; i++) {
    A[pos] = i;
    pos++;
  }
  if ((N - K) % 2 == 1) {
    for (int i = 1; i <= K - 1; i++) {
      A[pos] = i;
      pos++;
    }
  } else {
    for (int i = K - 1; i >= 1; i--) {
      A[pos] = i;
      pos++;
    }
  }
  for (int i = 0; i < N; i++) {
    T += S[A[i] - 1];
  }
  cout << T << endl;
  return 0;
}