#include <bits/stdc++.h>

using namespace std;

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)

int main(){
   cin.tie(0);
   ios::sync_with_stdio(false);

   int n,m;
   cin >> n >> m;

   char a[n][m];
   rep(i,n){
      rep(j,m){
         cin >> a[i][j];
      }
   }

   rep(i,n){
      rep(j,m){
        if(a[i][j] == 'L' && a[i][j + 1] == 'O' && a[i][j + 2] == 'V' && a[i][j + 3] == 'E'){
           cout << "YES" << endl;
           return 0;
        }
      }
   }

   cout << "NO" << endl;

   return 0;
}