#include<bits/stdc++.h>
using namespace std;
const int maxn=8000;
const int dx[5]={0,1,-1,0,0};
const int dy[5]={0,0,0,1,-1};
int n,m,x,y;
int u,v,d;
int match[maxn],vis[maxn];
int tot=0,pre[maxn],son[maxn],now[maxn];
int id[1200][1200],ok[maxn],cnt=0,sum=0,del[maxn];
int to[maxn],tmp[maxn];
char s[1200][1200];
void put(int x,int y)
{
	pre[++tot]=now[x];
	now[x]=tot;
	son[tot]=y;
}
int dfs(int x,int tag)
{
	if(vis[x]==tag)
		return 0;
	vis[x]=tag;
	for(int p=now[x];p;p=pre[p])
	{
		int t=son[p];
		if(del[t])
			continue;
		if(!match[t]||dfs(match[t],tag))
		{
			match[t]=x,match[x]=t;
			return 1;
		}
	}
	return 0;
}
void calc(int x,int tag)
{
	if(del[x]||vis[x]==tag)
		return ;
	vis[x]=tag;sum--;
	for(int p=now[x];p;p=pre[p])
	{
		int t=son[p];
		if(del[t])
			continue;
		calc(match[t],tag);
	}
}
int get(int x,int tag)
{
	if(vis[x]==tag)
		return 0;
	if(!match[x])
		return 1;
	vis[x]=tag;
	for(int p=now[x];p;p=pre[p])
	{
		int t=son[p];
		if(get(match[t],tag))
			return 1;
	}
	return 0;
}
int main()
{
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)
		scanf("%s",s[i]+1);
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
			if(s[i][j]=='.')
			{
				id[i][j]=++cnt,ok[cnt]=((i+j)&1);
				if((i+j)&1)
					x++;
				else
					y++;
			}
	if((x+y)%2==1||abs(x-y)>=3)
		return printf("%lld\n",min(1000000ll,1ll*(x+y)*(x+y-1)/2)),0;
	if(x>=1001)
		return puts("1000000"),0;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
			if(s[i][j]=='.')
				for(int k=1;k<=4;k++)
				{
					int p=i+dx[k],q=j+dy[k];
					if(p&&q&&p<=n&&q<=m&&s[p][q]=='.')
						put(id[i][j],id[p][q]);
				}
	int ans=0;
	for(int i=1;i<=cnt;i++)
		if(ok[i]&&dfs(i,i))
			ans++;
	if(x+y-2*ans>2)
		return printf("%lld\n",min(1000000ll,1ll*(x+y)*(x+y-1)/2)),0;
	if(x==y&&ans==x)
	{
		sum=x*(x-1);
		for(int i=1;i<=cnt;i++)
			if(ok[i])
			{
				sum+=y;
				int t=match[i];
				del[i]=1;match[i]=match[t]=0;
				calc(t,1e9-i);
				del[i]=0;match[i]=t,match[t]=i;
			}
		printf("%d\n",min(1000000,sum));
	}
	if(x==y&&ans==x-1)
	{
		sum=x*(x*2-1);
		for(int i=1;i<=cnt;i++)
			if(match[i])
				to[i]=get(i,1e9-i);
			else
				to[i]=1;
		int ct=0;
		for(int i=1;i<=cnt;i++)
			if(!ok[i])
				ct+=to[i];
		for(int i=1;i<=cnt;i++)
			if(ok[i]&&to[i])
				sum-=ct;
		printf("%d\n",min(1000000,sum));
	}
	if(abs(x-y)==2)
	{
		if(x>=820)
			return puts("1000000"),0;
		int sum=1ll*(x+y)*(x+y-1)/2,p=1,po=1e9;
		if(x==y-2)
			p=0;
		for(int i=1;i<=cnt;i++)
			if(ok[i]==p)
				for(int j=i+1;j<=cnt;j++)
					if(ok[j]==p)
					{
						for(int k=1;k<=cnt;k++)
							tmp[k]=match[k];
						del[i]=del[j]=1;
						int p=match[i],q=match[j];
						match[p]=match[q]=0;
						if((!p||dfs(p,po--))&&(!q||dfs(q,po--)))
							sum--;
						for(int k=1;k<=cnt;k++)
							match[k]=tmp[k];
						del[i]=del[j]=0;
					}
		printf("%d\n",min(1000000,sum));
	}
	
	return 0;
}