#include <bits/stdc++.h>
using namespace std;
template <class t>
t mag(t a) {
  return a > 0 ? a : -a;
}
template <class T, class U>
T cdiv(T num, U den) {
  return (num / den) + ((num % den) > 0);
}
std::ifstream term("/dev/tty");
std::string tempstring;
using ll = int_fast64_t;
using ii = pair<int, int>;
using vi = vector<int>;
using vl = vector<ll>;
using vii = vector<ii>;
const int &sij = 1010;
const ll &mod = 1000000007ll;
struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};
struct h_pair {
  size_t operator()(const ii &x) const {
    return hash<ll>()(((ll)x.first) ^ (((ll)x.second) << 32));
  }
};
unordered_map<short, bool, custom_hash> mp[sij];
int n, k;
string s;
void dfs(short ind, int bal, vi &vec) {
  ;
  if (mp[ind][bal] == 1) return;
  if (ind == n and (bal == k or bal == -k)) {
    int ib = 0;
    for (auto &e : vec) {
      if (e == 0)
        cout << 'D';
      else if (e == 1)
        cout << 'W';
      else if (e == -1)
        cout << 'L';
    }
    exit(0);
  }
  if (ind == n) return;
  if (s[ind] == 'W') {
    if (bal == k - 1 and ind < n - 1) {
      mp[ind][bal] = 1;
      return;
    }
    vec.push_back(1);
    dfs(ind + 1, bal + 1, vec);
    vec.pop_back();
    mp[ind][bal] = 1;
    return;
  } else if (s[ind] == 'L') {
    if (bal == (-k + 1) and ind < n - 1) {
      mp[ind][bal] = 1;
      return;
    }
    vec.push_back(-1);
    dfs(ind + 1, bal - 1, vec);
    vec.pop_back();
    mp[ind][bal] = 1;
    return;
  } else if (s[ind] == 'D') {
    vec.push_back(0);
    dfs(ind + 1, bal, vec);
    vec.pop_back();
    mp[ind][bal] = 1;
    return;
  };
  if (!(bal == k - 1 and ind < n - 1)) {
    vec.push_back(1);
    dfs(ind + 1, bal + 1, vec);
    vec.pop_back();
  }
  if (!(bal == (-k + 1) and ind < n - 1)) {
    vec.push_back(-1);
    dfs(ind + 1, bal - 1, vec);
    vec.pop_back();
  }
  vec.push_back(0);
  dfs(ind + 1, bal, vec);
  vec.pop_back();
  mp[ind][bal] = 1;
}
int esc(int tcase) {
  cin >> n >> k >> s;
  vi vv;
  dfs(0, 0, vv);
  cout << "NO";
  return 0;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int tc = 1;
  for (int i = 1; i <= tc; i++) esc(i);
}
