#include <bits/stdc++.h>
using namespace std;
 
#define ll long long
#define ld long double
#define ar array
 
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
 
template <typename T> using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
 
#define pb push_back
#define all(c) (c).begin(), (c).end()
#define sz(x) (int)(x).size()
const int N = 2001;
char a[N][N];
int n , m;
int G[N][N] , B[N][N];

bool f(int mid)
{
    for(int j = 0 ; j <= m - mid; j++)
    {
        int cnt = 0;
        for(int i = 1 ; i <= n ; i++)
        {
            int good = G[i][mid + j] - G[i][j];
            int bad = B[i][mid + j] - B[i][j];
            if(good == mid || good == 0) ++cnt;
            else cnt = 0;
            if(cnt >= mid) return true;
        } 
    }
    return false;
}
 
void Solve()
{
    cin >> n >> m;
    for(int i = 1 ; i <= n ; i++)
    {
        for(int j = 1 ; j <= m ; j++)
        {
            cin >> a[i][j];
        }
    }
    for(int i = 1 ; i <= n ; i++)
    {
        for(int j = 1 ; j <= m ; j++)
        {
            G[i][j] = G[i][j - 1];
            B[i][j] = B[i][j - 1];
            if(a[i][j] == 'G') G[i][j] = G[i][j - 1] + 1;
            else B[i][j] = B[i][j - 1] + 1;
        }
    }
    
    ll l = 1 , r = min(n , m) + 1;
    while(r - l > 1)
    {
        int mid = (l + r) / 2;
        if(f(mid)) l = mid;
        else r = mid;
    }
    cout << (l) * (l) << '\n';
}
 
int main()
{
 
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
 
    int truongdoan = 1;
    //cin >> truongdoan;
 
    while(truongdoan-->0)
    {
        Solve();
    }
 
    return 0; 
}