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

#include<cstdio>

#include<cstring>

#include<cmath>

#include<algorithm>

#include<vector>

#include<map>

#include<set>

#include<queue>

#include<stack>

#include<ctime>

#include<iostream>

using namespace std;

typedef long long LL;

const double pi=acos(-1.0),eps=1e-;

void File()

{

    freopen("D:\\in.txt","r",stdin);

    freopen("D:\\out.txt","w",stdout);

}

template <class T>

inline void read(T &x)

{

    char c = getchar();

    x = ;

    while(!isdigit(c)) c = getchar();

    while(isdigit(c))

    {

        x = x *  + c - '';

        c = getchar();

    }

}

char s[][];

int n,m,ans,num[];

int f[];

void dfs(int x,int cnt,int st)

{

    if(cnt>=ans) return ;

    if(x==n)

    {

        if(f[st]<=cnt) ans=min(ans,cnt);

        return ;

    }

    dfs(x+,cnt+,st);

    dfs(x+,cnt,st|num[x]);

}

int lowbit(int x)

{

    return x&(-x);

}

int main()

{

    freopen("input.txt","r",stdin);

    freopen("output.txt","w",stdout);

    for(int i=;i<(<<);i++) f[i]=f[i-lowbit(i)]+;

    scanf("%d%d",&n,&m);

    for(int i=;i<n;i++)

    {

        scanf("%s",s[i]);

        for(int j=;j<m;j++)

            if(s[i][j]=='*') num[i]=num[i]+(<<j);

    }

    ans=min(n,m); dfs(,,);

    printf("%d\n",ans);

    return ;

}