#include<stdio.h>
int main()
{
	int n, m;
	scanf("%d %d", &n, &m);
	int i, j;
	char s[55][55];
	for (i = 0; i < n; i++)
		scanf("%s", s[i]);
	for (i = 0; i < n; i++)
	{
		for (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')
			{
				printf("YES\n");
				return 0;
			}
		}
	}
	printf("NO\n");
	return 0;
}