#include <bits/stdc++.h>
using namespace std;

int main() {
	int n,m,a[1010][1010],s=0,ans=0;
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>a[i][j];
			if(a[i][j]=='.') ans++;
		}
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			int answer=0;
			if(a[i][j]=='#') continue;
			if(i!=1&&a[i-1][j]=='#')answer++;
			if(i!=n&&a[i+1][j]=='#')answer++;
			if(j!=1&&a[i][j-1]=='#')answer++;
			if(j!=n&&a[i][j+1]=='#')answer++;
			if(answer>s) s=answer;
		}
	}
	cout<<ans+s; 
	return 0;
}