#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <map>
#include <cmath>
#include <iomanip>
#include <queue>
#include <stack>
#include <functional>
#define rep(i,n) for(int i=0;i<n;i++)
using ll = long long;
using namespace std;
ll n, m, ans = 0;
int main() {
	string A[101];
	cin >> n >> m;
	rep(i, n) cin >> A[i];
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m-4; j++)
			if (A[i][j] == 'L'&&A[i][j + 1] == 'O'&&A[i][j + 2] == 'V'&&A[i][j + 3] == 'E') {
				ans = 1;
				break;
			}
	if (ans == 1)
		cout << "YES" << endl;
	else
		cout << "NO" << endl;
	return 0;
}