#include <bits/stdc++.h>
using namespace std;
int n, m, x, y, k;
pair<int, int> poshti[1001][2002];
bool a[1001][2002];
string s;
char f[1001][2002];
void ja(int xx, int yy) {
  if (f[xx][yy] == '\0') return;
  ja(poshti[xx][yy].first, poshti[xx][yy].second);
  cout << f[xx][yy];
}
int main() {
  cin >> n >> k >> s;
  a[0][k + 1] = 1;
  for (int i = 0; i < n - 1; i++) {
    for (int j = 2; j <= 2 * k; j++) {
      if (s[i] == 'D') {
        a[i + 1][j] = a[i][j];
        f[i + 1][j] = s[i];
        poshti[i + 1][j] = make_pair(i, j);
        continue;
      }
      if (s[i] == 'L') {
        a[i + 1][j] = a[i][j + 1];
        f[i + 1][j] = s[i];
        poshti[i + 1][j] = make_pair(i, j + 1);
        continue;
      }
      if (s[i] == 'W') {
        a[i + 1][j] = a[i][j - 1];
        f[i + 1][j] = s[i];
        poshti[i + 1][j] = make_pair(i, j - 1);
        continue;
      }
      if (a[i][j] >= a[i][j + 1] && a[i][j] >= a[i][j - 1]) {
        a[i + 1][j] = a[i][j];
        f[i + 1][j] = 'D';
        poshti[i + 1][j] = make_pair(i, j);
        continue;
      }
      if (a[i][j + 1] >= a[i][j] && a[i][j + 1] >= a[i][j - 1]) {
        a[i + 1][j] = a[i][j + 1];
        f[i + 1][j] = 'L';
        poshti[i + 1][j] = make_pair(i, j + 1);
        continue;
      }
      if (a[i][j - 1] >= a[i][j + 1] && a[i][j - 1] >= a[i][j]) {
        a[i + 1][j] = a[i][j - 1];
        f[i + 1][j] = 'W';
        poshti[i + 1][j] = make_pair(i, j - 1);
        continue;
      }
    }
  }
  for (int i = n - 1; i < n; i++) {
    for (int j = 1; j <= 2 * k + 1; j++) {
      if (s[i] == 'D') {
        a[i + 1][j] = a[i][j];
        f[i + 1][j] = s[i];
        poshti[i + 1][j] = make_pair(i, j);
        continue;
      }
      if (s[i] == 'L') {
        a[i + 1][j] = a[i][j + 1];
        f[i + 1][j] = s[i];
        poshti[i + 1][j] = make_pair(i, j + 1);
        continue;
      }
      if (s[i] == 'W') {
        a[i + 1][j] = a[i][j - 1];
        f[i + 1][j] = s[i];
        poshti[i + 1][j] = make_pair(i, j - 1);
        continue;
      }
      if (a[i][j] >= a[i][j + 1] && a[i][j] >= a[i][j - 1]) {
        a[i + 1][j] = a[i][j];
        f[i + 1][j] = 'D';
        poshti[i + 1][j] = make_pair(i, j);
        continue;
      }
      if (a[i][j + 1] >= a[i][j] && a[i][j + 1] >= a[i][j - 1]) {
        a[i + 1][j] = a[i][j + 1];
        f[i + 1][j] = 'L';
        poshti[i + 1][j] = make_pair(i, j + 1);
        continue;
      }
      if (a[i][j - 1] >= a[i][j + 1] && a[i][j - 1] >= a[i][j]) {
        a[i + 1][j] = a[i][j - 1];
        f[i + 1][j] = 'W';
        poshti[i + 1][j] = make_pair(i, j - 1);
        continue;
      }
    }
  }
  if (a[n][1] == 1) {
    return ja(n, 1), 0;
  }
  if (a[n][2 * k + 1] == 1) {
    return ja(n, 2 * k + 1), 0;
  }
  cout << "NO";
  return 0;
}
