60求调，必回关

#include<bits/stdc++.h>
using namespace std;
int n,m,ans1,ans,zd=-2147483647;
char a[1001][1001];
int main(){
	cin>>n>>m;
	for(int i=0;i<n;i++){
		cin>>a[i];
	}
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
			if(a[i][j]=='.'){
				int f=1;
				if(i+1<n){
					if(a[i+1][j]=='#'){f=0;continue;}
				}if(j+1<m){
					if(a[i][j+1]=='#'){f=0;continue;}
				}if(i-1>=0){
					if(a[i-1][j]=='#'){f=0;continue;}
				}if(j-1>=0){
					if(a[i][j-1]=='#'){f=0;continue;}
				}if(f==1)ans1++;
			} 
		}
	}
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
			int x=1;
			if(a[i][j]=='#'){
				if(i+1<n){
					if(a[i+1][j]=='.'){x++;}
				}if(j+1<m){
					if(a[i][j+1]=='.'){x++;}
				}if(i-1>=0){
					if(a[i-1][j]=='.'){x++;}
				}if(j-1>=0){
					if(a[i][j-1]=='.'){x++;}
				}
				a[i][j]='.';
				if(i+1<n){
					if(a[i+1][j]=='#'){x--;}
				}else if(j+1<m){
					if(a[i][j+1]=='#'){x--;}
				}else if(i-1>=0){
					if(a[i-1][j]=='#'){x--;}
				}else if(j-1>=0){
					if(a[i][j-1]=='#'){x--;}
				}
				a[i][j]='#';
			}if(x>zd){
				zd=x;
			}
		}
	}
	ans=ans1+zd;
	cout<<ans<<endl;
	return 0;
}