#include <bits/stdc++.h>
using namespace std;
char flip(char x) { return x == 'B' ? 'W' : 'B'; }
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int N, K;
  cin >> N >> K;
  string s;
  cin >> s;
  vector<char> t(s.begin(), s.end());
  int start = -1;
  for (int i = 0; i < N; ++i) {
    if (t[i] == t[(i + 1) % N]) {
      start = (i + 1) % N;
      break;
    }
  }
  if (start == -1) {
    if (K % 2 == 1) {
      for (int i = 0; i < N; ++i) {
        t[i] = flip(t[i]);
      }
    }
    for (int i = 0; i < N; ++i) {
      cout << t[i];
    }
    cout << "\n";
    return 0;
  }
  for (int i = 0; i < start; ++i) {
    t.push_back(t[i]);
  }
  for (int i = start + 1; i < start + N - 1; ++i) {
    if (t[i] == t[i - 1]) continue;
    int j = i;
    while (j < start + N && t[j] != t[j - 1]) {
      j++;
    }
    j -= 2;
    if (i > j) continue;
    char left = t[i - 1];
    char right = t[j + 1];
    for (int k = 0; k < K; ++k, ++i, --j) {
      if (i > j) break;
      t[i] = left;
      t[j] = right;
    }
    if (K % 2 == 1) {
      for (int k = i; k <= j; ++k) {
        t[k] = flip(t[k]);
      }
    }
    i = j + 1;
  }
  for (int i = 0; i < N; ++i) {
    cout << (i < start ? t[i + N] : t[i]);
  }
  cout << "\n";
  return 0;
}
