#include "bits/stdc++.h"              // only gcc
using namespace std;                  // std::cout, std::endl

#pragma region TEMPLATE
constexpr auto INF = 1000000000000;   //10^12;;
constexpr auto MOD = 1000000007;      //10^9+7;;
constexpr auto EPS = 1e-9;
constexpr auto PI  = 3.141592653589793238462643383279;
#define endl '\n';                    // std::endl => '\n'
#define nl  cout << endl;
#define ALL(v) v.begin(), v.end() 
#define RALL(x) (x).rbegin(), (x).rend()
#define SORT(v) sort(ALL(v)) 
#define RSORT(v) sort(RALL(v))
#define SZ(x) ((int)(x).size())
#define FOR(i, j, k) for (int i=j ; i<k ; i++)
#define RFOR(i, j, k) for (int i=j ; i>=k ; i--)
#define REP(i, j) FOR(i, 0, j)
#define RREP(i, j) RFOR(i, j, 0)
#define FOREACH(it,l) for (auto it = l.begin(); it != l.end(); it++)
#define YES(p) cout << (p ? "YES":"NO") << endl;
#define Yes(p) cout << (p ? "Yes":"No") << endl;
template<class T = int>T in(){T x; cin >> x; return x; }   // read
template<class T> void out(T value){ cout << value << endl; }// write
template<class T> bool chmax(T& a,const T& b){ if (a < b){ a = b; return 1; } return 0; } // change max
template<class T> bool chmin(T& a,const T& b){ if (b < a){ a = b; return 1; } return 0; } // change min
// initialize fast io
struct Fast_IO {
    const int prec = 10;
    Fast_IO() {
        cin.tie(nullptr);
        ios_base::sync_with_stdio(false);
        cout << fixed << setprecision(prec);
    }
} fast_io;
#pragma endregion

using  VI = vector<int>;
using  ll = long long;
using VLL = vector<ll>;
signed main() {
    Fast_IO();
      
    int N, K; cin >> N >> K;
    string S = in<string>();
    REP(i, N - K + 1) {
        swap(S[i], S[i+K-1]);
    }
    out(S);
    return 0;
}