#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

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

    int N,M; cin >> N >> M;
    vector<vector<char>> s(N, vector<char>(M));
    rep(i,N)rep(j,M) cin >> s[i][j];
    rep(i,N)rep(j,M-3){
        if(s[i][j+0] == 'L' 
        && s[i][j+1] == 'O'
        && s[i][j+2] == 'V'
        && s[i][j+3] == 'E'){
            cout << "YES" << endl;
            return 0;
        }
    }
    cout << "NO" << endl;
}