#include<iostream>
#include <algorithm>
#include<string>
#include <bitset>
#include <vector>
using namespace std;
int main()
{
	//int a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, ans = 0;
	long a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, i = 0, j = 0, k = 0, l = 0, ans = 0;
	//cout << LONG_MAX << endl;
	//string s[1001];

	char x[10000];
	cin >> a;
	cin >> b;
	for (c = 0; c < a*b; c++)
	{
		cin >> x[c];
	}
	for (c = 0; c < a*b - 3; c++)
	{
		if (x[c] == 'L'&&x[c + 1] == 'O'&&x[c + 2] == 'V'&&x[c + 3] == 'E')
		{
			cout << "YES" << endl;
			return 0;
		}
	}
	cout << "NO" << endl;




	//cout << ans << endl;
	return 0;
}