#include<cstdio>
const int N=202;
int n,m,ans,you[N][N],xia[N][N];
char s[N];
inline int max(int x,int y) { return x>y?x:y; }
int main()
{
	freopen("fortmoo.in","r",stdin);
	freopen("fortmoo.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(int i=1,k;i<=n;i++)
	{
		scanf("%s",s+1);
		for(int j=1;j<=m;j++)
	 	  if(s[j]=='.')
	 	  {
	 	  	you[i][j]=j;k=j-1;
	 	  	while(k&&you[i][k]==j-1) you[i][k--]=j;
	 	  	xia[i][j]=i;k=i-1;
	 	  	while(k&&xia[k][j]==i-1) xia[k--][j]=i;
	 	  }
	 }
	for(int i=1;i<=n;i++)
	  for(int j=1;j<=m;j++)
	    for(int k=i;k<=xia[i][j];k++)
	      for(int t=you[i][j];t>=j;t--)
	        if(t<=you[k][j]&&k<=xia[i][t])
			  {ans=max(ans,(k-i+1)*(t-j+1));break;}
	printf("%d\n",ans);
}