#include <bits/stdc++.h>
using namespace std;
int n, k;
int dp[1005][2005];
char s[2005];
int main() {
  ios_base::sync_with_stdio(false);
  for (int i = 0; i < 1005; ++i)
    for (int j = 0; j < 2005; ++j) dp[i][j] = 0x3F3F3F3F;
  cin >> n >> k >> (s + 1);
  dp[0][1000] = 0;
  for (int i = 0; i < n; ++i) {
    for (int j = -k + 1; j <= k - 1; ++j) {
      if (dp[i][j + 1000] == 0x3F3F3F3F) continue;
      int L = -1, R = 1;
      if (s[i + 1] == 'L')
        L = R = -1;
      else if (s[i + 1] == 'D')
        L = R = 0;
      else if (s[i + 1] == 'W')
        L = R = 1;
      for (; L <= R; ++L) dp[i + 1][j + 1000 + L] = L;
    }
  }
  int y = n, x = k + 1000;
  if (dp[y][x] == 0x3F3F3F3F) x = -k + 1000;
  if (dp[y][x] == 0x3F3F3F3F) {
    cout << "NO\n";
    return 0;
  }
  while (y) {
    if (dp[y][x] == 1)
      s[y] = 'W';
    else if (dp[y][x] == 0)
      s[y] = 'D';
    else if (dp[y][x] == -1)
      s[y] = 'L';
    x -= dp[y][x];
    --y;
  }
  cout << (s + 1) << endl;
  return 0;
}
