n,k=map(int,input().split())
if n==1 or k==1:
    print(n-1)
    exit()

S=[input() for _ in range(n)]
X=[list(int(s) for s in S[i]) for i in range(n)]

A=[sum(x) for x in X]
entry_set=set(S)


max_A=max(A)
if max_A==4*k:
    print(n-1)
    exit()

remove_set=set()
for i in range(n):
    if A[i]==max_A:
        entry_set.remove(S[i])
        for j in range(k):
            if X[i][j]==0:
                continue
            remove_set.add("".join([str(X[i][l]-1) if l==j else str(X[i][l]) for l in range(k)]))
            

num=max_A-1
ans=0
while(entry_set):
    for i in range(n):
        if A[i]==num:
            if S[i] in remove_set:
                ans+=1
            else:
                remove_set.add(S[i])
            entry_set.remove(S[i])
    _remove_set=set()
    for r in remove_set:
        for j in range(k):
            if r[j]=="0":
                continue
            R=list(r)
            R[j]=str(int(R[j])-1)
            _remove_set.add("".join(R))
    remove_set=_remove_set
    num-=1
    if num==-1:
        break

print(ans)