#include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;

const int INF = (1 << 30) - 1;
const ll INF64 = ((ll)1 << 62) - 1;
const double PI = 3.1415926535897932384626433832795;

const int dx[] = { 0, 1, 0, -1 };
const int dy[] = { -1, 0, 1, 0 };

bool solve(int n, int m, const vector<string> img) {
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m - 3; j++) {
			if (img[i][j] == 'L'
				&& img[i][j + 1] == 'O'
				&& img[i][j + 2] == 'V'
				&& img[i][j + 3] == 'E') {
				return true;
			}
		}
	}

	return false;
}

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

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

	vector<string> img(n);
	for (int i = 0; i < n; i++) {
		cin >> img[i];
	}

	cout << (solve(n, m, img) ? "YES" : "NO") << endl;
	return 0;
}