#include <vector>
#include <iostream>
using namespace std;
int main() {
	int N, K;
	cin >> N >> K; string S;
	cin >> S;
	for (int i = 0; i <= N - K; ++i) {
		swap(S[i], S[i + K - 1]);
	}
	cout << S << endl;
	return 0;
}