I,R=input,range
N,K=map(int,I().split())
M=set()
P=pow(5,K-1)
for i in R(N):
	S=int(I(),5)
	b=0
	for m in M:
		s,t,p=S,m,P
		for j in R(K):
			b+=t<s
			s,t,p=s%p,t%p,p//5
		if 1-b:break
	else:
		L=[]
		for m in M:
			s,t,p,b=S,m,P,1
			for j in R(K):
				b*=t<=s
				s,t,p=s%p,t%p,p//5
			if b:L.append(m)
		for m in L:M.remove(m)
		M.add(S)
print(N-len(M))