#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;

int main() {
  int N, M; cin >> N >> M;
  if(M < 4){
    cout << "NO" << endl;
    return 0;
  }
  for(int i = 0; i < N; i++){
    string S; cin >> S;
    int flag = S.find("LOVE");
    if(flag != -1){
      cout << "YES" << endl;
      return 0;
    }
  }
  cout << "NO" << endl;
}