#include<iostream>
#include<math.h>
#include<string.h>
#include<vector>
#include<algorithm>
#include<iomanip>
#include<deque>
using namespace std;

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