#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <stdio.h>
#include <cstring>
#include <queue>
#include <stack>
#include <functional>
using namespace std;
#define Would
#define you


int main() {
	char k[55][55];
	int a, b;
	cin >> a >> b;
	for (int i = 0; i < a; ++i) {
		for (int j = 0; j < b; ++j) {
			cin >> k[i][j];
		}
	}
	for (int i = 0; i < a; ++i) {
		for (int j = 0; j < b - 3; ++j) {
			if (k[i][j] == 'L'&&k[i][j + 1] == 'O'&&k[i][j + 2] == 'V'&&k[i][j + 3] == 'E') {
				cout << "YES" << endl;
				return 0;
			}
		}
	}
	cout << "NO" << endl;
}