#include <iostream>
using namespace std;
#define REP(i,n) for(i=1;i<=n;i++)
short x,y,w[505][505];char map[505][505];int main(){int i,j,k;while(cin>>y>>x,y){REP(i,y)cin>>map[i]+1;memset(w,0,sizeof(w));REP(i,y)REP(j,x)w[i][j]=x-j+1;REP(i,y)REP(j,x)if(map[i][j]=='.')continue;else for(k=j;k>0;k--)if(w[i][k]>j-k)w[i][k]=j-k;int max=0;REP(i,y)REP(j,x){int h=1;if(!w[i][j])continue;for(k=i-1;w[k][j]>=w[i][j];k--)h++;for(k=i+1;w[k][j]>=w[i][j];k++)h++;if(max<w[i][j]*h)max=w[i][j]*h;}cout<<max<<endl;}}