#pragma comment(linker, "/STACK:1024000000,1024000000")

#include <cstdio>

#include <string>

#include <cstdlib>

#include <cmath>

#include <iostream>

#include <cstring>

#include <set>

#include <queue>

#include <algorithm>

#include <vector>

#include <map>

#include <cctype>

#include <cmath>

#include <stack>

#include <sstream>

#define debug() puts("++++");

#define gcd(a, b) __gcd(a, b)

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1|1

#define freopenr freopen("in.txt", "r", stdin)

#define freopenw freopen("out.txt", "w", stdout)

using namespace std;

typedef long long LL;

typedef unsigned long long ULL;

typedef pair<int, int> P;

const int INF = 0x3f3f3f3f;

const double inf = 0x3f3f3f3f3f3f;

const double PI = acos(-1.0);

const double eps = 1e-8;

const int maxn = 2000 + 10;

const int mod = 1e9 + 7;

const int dr[] = {-1, 0, 1, 0};

const int dc[] = {0, 1, 0, -1};

const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};

int n, m;

const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

inline bool is_in(int r, int c){

  return r >= 0 && r < n && c >= 0 && c < m;

}

vector<string> v;

int V;

vector<int> G[maxn];

int match[maxn];

bool used[maxn];

void addEdge(int u, int v){

  G[u].push_back(v);

  G[v].push_back(u);

}

bool dfs(int v){

  used[v] = true;

  for(int i = 0; i < G[v].size(); ++i){

    int u = G[v][i], w = match[u];

    if(w < 0 || !used[w] && dfs(w)){

      match[v] = u;

      match[u] = v;

      return true;

    }

  }

  return false;

}

int solve(){

  int res = 0;

  memset(match, -1, sizeof match);

  for(int v = 0; v < V; ++v)  if(match[v] < 0){

    memset(used, 0, sizeof used);

    if(dfs(v))  ++res;

  }

  return res;

}

bool judge(int i, int j){

  int cnt = 0, k = 0;

  while(k < n){

    if(v[i][k] != v[j][k]) ++cnt;

    ++k;

  }

  return cnt == 1;

}

int main(){

  while(cin >> n >> m && m+n){

    v.clear();

    for(int i = 0; i < m ; ++i){

      string s;

      cin >> s;

      if(s.find('*') != string::npos){

        int pos = s.find('*');

        s[pos] = '1';

        v.push_back(s);

        s[pos] = '0';

      }

      v.push_back(s);

    }

    sort(v.begin(), v.end());

    V = unique(v.begin(), v.end()) - v.begin();

    for(int i = 0; i < V; ++i)  G[i].clear();

    for(int i = 0; i < V; ++i)

      for(int j = i+1; j < V; ++j)

        if(judge(i, j))  addEdge(i, j);

    printf("%d\n", V - solve());

  }

  return 0;

}