/** gnu specific **/
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
/** contains everything I need in std **/
#include <bits/stdc++.h>

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(S) ((int)S.size())
#define FOR(i, st_, n) for(int i = st_; i < n; ++i)
#define RFOR(i, n, end_) for(int i = (n)-1; i >= end_; --i)
#define x first
#define y second
#define pb push_back
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef pair<double, double> pdd;
typedef unsigned long long ull;
typedef long double LD;
typedef pair<ull, ull> pull;
using namespace __gnu_pbds;
typedef tree<ll, null_type, less<>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
using namespace std;
#ifdef ONPC
mt19937 rnd(228);
#else
mt19937 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());
#endif


bool is_good(const vector<string>& a, int X)
{
	int n=sz(a),m=sz(a[0]);
	vector<vector<bool>> b(n, vector<bool>(m,false));
	FOR(i,0,n)
	{
		int cg=0;		
		FOR(j,0,X)if(a[i][j]=='G')++cg;
		if(cg==0||cg==X) b[i][0]=1;
		FOR(j,X,m)
		{
			if(a[i][j]=='G')++cg;
			if(a[i][j-X]=='G')--cg;
			if(cg==0 || cg==X) b[i][j-X+1]=1;
		}
	}
	FOR(i,0,m-X+1)
	{
		int o=0;
		FOR(j,0,X)if(b[j][i])++o;
		if(o==X)return true;
		FOR(j,X,n)
		{
			if(b[j][i])++o;
			if(b[j-X][i])--o;
			if(o==X)return true;
		}
	}
	return false;
}

int solve()
{
	int n,m;
	if(!(cin>>n>>m))
		return 1;
	vector<string> a(n);
	FOR(i,0,n)cin>>a[i];
	
	int l = 1, r = min(n,m);
	while(r-l>1)
	{
		int mid=(l+r)/2;
		if(is_good(a, mid))
			l=mid;
		else
			r=mid;
	}
	if(is_good(a,r))
		l=r;
	cout<<l*l<<'\n';
    return 0;
}

int32_t main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int TET = 1e9;
    //cin >> TET;
    for (int i = 1; i <= TET; i++)
    {
        if (solve())
        {
            break;
        }
#ifdef ONPC
        cout << "__________________________" << endl;
#endif
    }
#ifdef ONPC
    cerr << endl << "finished in " << clock() * 1.0 / CLOCKS_PER_SEC << " sec" << endl;
#endif
}