#include <iostream>
using namespace std;
int main(){
  int h,w;
  cin >> h >> w;
  string ok = "NO";
  if(w >= 4){
    for(int i = 0; h > i; i++){
      string tmp; cin >> tmp;
      for(int j = 0; w-3 > j; j++){
        if(tmp[j] == 'L' && tmp[j+1] == 'O' && tmp[j+2] == 'V' && tmp[j+3] == 'E') ok = "YES";
      }
    }
  }
  cout << ok << endl;
}