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

string s[100];

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < n; i++) {
        cin >> s[i];
        for (int j = 0; j < m; j++) {
            if (j + 3 < m && s[i][j] == 'L' && s[i][j+1] == 'O' && s[i][j+2] == 'V' && s[i][j+3] == 'E') {
                cout << "YES\n";
                return 0;
            }
         }
    }
    cout << "NO\n";



    return 0;
}