#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N=1010;
int t,l[N],r[N],dp[N][N],n,m,a[N][N],ans=0,stk[N],root=0,vis[N];
char x;
int dfs(int i,int x){
	if(x==0)return 0;
	int siz=dfs(i,l[x]);
	siz+=dfs(i,r[x]);
	ans=max(ans,(siz+1)*dp[i][x]);
	return siz+1; 
}
signed main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>x;
			if(x=='F'){
				a[i][j]=1;
			}
			else{
				a[i][j]=0;
			}
		}
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			if(a[i][j]==0){
				dp[i][j]=0;
			}
			else{
				dp[i][j]=dp[i-1][j]+1;
			}
		}
	}
	for(int i=1;i<=n;i++){
		int top=0;
		for(int j=1;j<=m;j++){
			int k=top;
			while(k>0 && dp[i][stk[k]]>dp[i][j]){
				k--;
			}
			if(k!=0){
				r[stk[k]]=j;
			}
			if(k<top){
				l[j]=stk[k+1];
			}
			stk[++k]=j;
			top=k;
		}
		for(int j=1;j<=m;j++)vis[j]=0;
		for(int j=1;j<=m;j++){
			vis[l[j]]=1;
			vis[r[j]]=1;
		}
		for(int j=1;j<=m;j++){
			if(vis[j]==0){
				root=j;
				break;
			}
		}
		t=dfs(i,root);
	}
	cout<<ans*3<<"\n"; 
	return 0;
}
/*
4 6
RRRFRR
RRFFRR
FRFFRF
FFFFFF
*/

可随时叫我亦可私信轰炸。