#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int N=1e3+10;
const int INF=0x3f3f3f3f;
inline int read(){ll x=0,f=1;char ch=getchar();while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=getchar();}while (ch>='0'&&ch<='9'){x=x*10+ch-48;ch=getchar();}return x*f;}
ll n,m,cnt,dx[4]={1,-1,0,0},dy[4]={0,0,-1,1},sum,ans;
char a[N][N];
bool check(ll x,ll y){
    for(int i=0;i<4;i++){
        ll xx=x+dx[i],yy=y+dy[i];
        if(xx>=1&&xx<=n&&yy>=1&&yy<=m&&a[xx][yy]=='#'){
        	return 0;
		}
    }
    return 1;
}
int main(){
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
    cin>>n>>m;
    for(int i=1;i<=n;i++){
    	for(int j=1;j<=m;j++){
    		cin>>a[i][j];
		}
	}
    for(int i=1;i<=n;i++){
    	for(int j=1;j<=m;j++){
        	if(a[i][j]=='.'&&check(i,j)){
        		cnt++;
			}
			else if(a[i][j]=='#'){
                a[i][j]='.';
                sum=0;
                if(check(i,j)){
                	sum++;
				}
                for(int k=0;k<4;k++){
                    ll xx=i+dx[k],yy=j+dy[k];
                    if(xx>=1&&xx<=n&&yy>=1&&yy<=m&&a[xx][yy]=='.'&&check(xx,yy)){
                    	sum++;
					}
                }
				a[i][j]='#';
            }
            ans=max(ans,sum);
    	}
	}
    cout<<ans+cnt;
}