N, M = map(int, raw_input().split())
word = 'LOVE'
flag = False
for i in range(0, N):
	s = raw_input()
	for j in range(0, M-4):
		for k in range(0, 4):
			if s[j+k] != word[k]: break
			if k == 3: flag = True
		if flag: break
if flag: print 'YES'
else: print 'NO'