#include <bits/stdc++.h>
using namespace std;
inline long long getnum() {
  char c = getchar();
  long long num, sign = 1;
  for (; c < '0' || c > '9'; c = getchar())
    if (c == '-') sign = -1;
  for (num = 0; c >= '0' && c <= '9';) {
    c -= '0';
    num = num * 10 + c;
    c = getchar();
  }
  return num * sign;
}
char S[200020];
char T[200020];
vector<pair<int, int> > V;
int main() {
  int n = getnum(), k = getnum();
  gets(T + 3);
  int rot = 3;
  for (rot = 3; rot <= n + 2; rot++) {
    if (T[rot] == T[rot + 1]) break;
  }
  for (int i = 3, j = rot; i <= n + 2; i++, j++) {
    if (j == n + 3) j = 3;
    S[i] = T[j];
  }
  S[1] = S[n + 1];
  S[2] = S[n + 2];
  S[n + 3] = S[3];
  S[n + 4] = S[4];
  for (int i = 0; i <= n + 4;) {
    int x = i;
    while (S[i] == S[x] && i <= n + 4) i++;
    if (i - x > 1) V.push_back(make_pair(x, i - 1));
  }
  if (V.size() == 0) {
    if (k % 2) {
      for (int i = 3; i <= n + 2; i++) S[i] = 'B' + 'W' - S[i];
    }
    S[n + 3] = 0;
    printf("%s", S + 3);
    return 0;
  }
  for (int i = 0; i < V.size() - 1; i++) {
    int l = V[i].second;
    int r = V[i + 1].first;
    int t = min(k, (r - l) / 2);
    l++, r--;
    for (int tt = 1; tt <= t; l++, tt++) S[l] = S[V[i].second];
    for (int tt = 1; tt <= t; r--, tt++) S[r] = S[V[i + 1].first];
    for (; l <= r; l++) S[l] = 'B' + 'W' - S[l - 1];
  }
  T[n + 3] = 0;
  for (int i = rot, j = 3; j <= n + 2; i++, j++) {
    if (i == n + 3) i = 3;
    T[i] = S[j];
  }
  printf("%s", T + 3);
}
