#include<iostream>
#include<cstdio>
using namespace std;
char ma[50005][505];
int b[50005];
int f[50005];
int w,h;
int main(){
    freopen("snow.in","r",stdin);
    freopen("snow.out","w",stdout);
    cin>>w>>h;
    for(int i=1;i<=h;i++){
        for(int j=1;j<=w;j++){
            cin>>ma[i][j];
            if(ma[i][j]=='*'){
                int l=max(1,j-(h-i));
                int r=min(w,j+(h-i));
                b[l]++;
                b[r+1]--;
            }
        }
    }
    int ans=0;
    for(int i=1;i<=w;i++){
        f[i]=f[i-1]+b[i];
        ans=max(ans,f[i]);
    }
    cout<<ans<<endl;
    return 0;
}