#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <sstream>
#include <cassert>
#include <list>
using namespace std;
static const double EPS = 1e-10;
typedef long long ll;
typedef pair<int,int> PI;
typedef vector<int> vi;
#ifndef M_PI
#define M_PI 3.1415926535
#endif
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define F first
#define S second

int dx[]={0,1,0,-1},dy[]={1,0,-1,0};


main(){
  int h,w;
  while(cin>>h>>w,h|w){
    char gr[h][w];
    rep(i,h)scanf(" %s ",gr[i]);

    int dp[h+2][w+2];
    memset(dp,0,sizeof(dp));
    rep(i,h)rep(j,w){
      if(gr[i][j]=='.')dp[i+1][j+1]=dp[i][j+1]+1;
    }

    int ans=0;
    rep(i,h+2){
      stack<PI> st;
      rep(j,w+2){
	if(dp[i][j])st.push(mp(j,dp[i][j]));
	
	stack<PI> nst;
	while(!st.empty()){
	  int cj=st.top().F,ta=st.top().S;
	  st.pop();
	  if(ta<=dp[i][j]){
	    ans=max(ans,ta*(j-cj+1));
	    nst.push(mp(cj,ta));
	  }else{
	    ans=max(ans,dp[i][j]*(j-cj+1));
	    nst.push(mp(cj,dp[i][j]));
	  }
	}
	st=nst;
      }
      //cout<<ans<<endl;
    }
    printf("%d\n",ans);
  }
}

	