#include <bits/stdc++.h>
using namespace std;

int main()
{
	int n, m;
	cin >> n >> m;
	vector<string> s( n );
	for( int i = 0; i < n; i++ ) {
		cin >> s[i];
	}

	string ans = "NO";
	for( int i = 0; i < n; i++ ) {
		for( int j = 0; j < m - 3; j++ ) {
			if( s[i][j] == 'L' && s[i][j + 1] == 'O' && s[i][j + 2] == 'V' && s[i][j + 3] == 'E' ) ans = "YES";
		}
	}

	cout << ans << endl;
}