#include "bits/stdc++.h"

using namespace std;
using ll = long long;
const double pi = acos(-1);
#define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
#define RFOR(i,a,b) for (ll i=(b)-1,__last_##i=(a);i>=__last_##i;i--)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define __GET_MACRO3(_1, _2, _3, NAME, ...) NAME
#define rep(...) __GET_MACRO3(__VA_ARGS__, FOR, REP)(__VA_ARGS__)
#define rrep(...) __GET_MACRO3(__VA_ARGS__, RFOR, RREP)(__VA_ARGS__)
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v) {
	REP(i, v.size()) { if (i)os << " "; os << v[i]; }return os;
}
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v) {
	REP(i, v.size()) { if (i)os << endl; os << v[i]; }return os;
}

int main() {
	ll n, m;
	
	cin >> n >> m;

	vector<string> v(n);

	REP(i, n) {
		cin >> v[i];
	}

	REP(i, n) {
		REP(j, m - 3) {
			if (v[i][j] == 'L' && v[i][j + 1] == 'O' && v[i][j + 2] == 'V' && v[i][j + 3] == 'E') {
				cout << "YES" << endl;
				return 0;
			}
		}
	}

	cout << "NO" << endl;
}