#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n, k;
  cin >> n >> k;
  long long tk = k;
  string s;
  cin >> s;
  vector<bool> col(n);
  for (long long i = 0; i < n; ++i) {
    if (s[i] == s[(i + 1) % n] || s[i] == s[(i - 1 + n) % n]) col[i] = 1;
  }
  long long cnt = 0;
  for (long long i = 0; i < n; ++i)
    if (!col[i]) ++cnt;
  queue<long long> u, d;
  for (long long i = 0; i < n; ++i) {
    if (!col[i] && col[(i + 1) % n])
      u.push(i);
    else if (!col[i] && col[(i - 1 + n) % n]) {
      d.push(i);
    }
  }
  vector<char> ans(n, 'E');
  for (long long i = 0; i < n; ++i)
    if (col[i]) ans[i] = s[i];
  while (k) {
    long long us = u.size(), ds = d.size();
    if (us + ds == 0) {
      break;
    }
    for (long long i = 0; i < us; ++i) {
      long long id = u.front();
      u.pop();
      if (!col[id]) ans[id] = ans[(id + 1) % n];
      col[id] = 1;
      if (!col[(id - 1 + n) % n]) {
        u.push((id - 1 + n) % n);
      }
    }
    for (long long i = 0; i < ds; ++i) {
      long long id = d.front();
      d.pop();
      if (!col[id]) ans[id] = ans[(id - 1 + n) % n];
      col[id] = 1;
      if (!col[(id + 1) % n]) {
        d.push((id + 1) % n);
      }
    }
    --k;
  }
  for (long long i = 0; i < n; ++i) {
    if (ans[i] != 'E')
      cout << ans[i];
    else {
      if (s[i] == 'W' && tk % 2) cout << 'B';
      if (s[i] == 'W' && (tk % 2) == 0) cout << 'W';
      if (s[i] == 'B' && tk % 2) cout << 'W';
      if (s[i] == 'B' && (tk % 2) == 0) cout << 'B';
    }
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  solve();
  return 0;
}
