#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

int rd() {
    int x = 0; 
    bool f = 0; 
    char c = getchar();
    for (; !isdigit(c); c = getchar()) f |= (c == '-');
    for (; isdigit(c); c = getchar()) x = x * 10 + (c ^ 48);
    return f ? -x : x;
}

#define fr        first
#define sc        second
#define mp        make_pair
#define pb        push_back
#define pii       pair<int, int>
#define all(s)    (s).begin(), (s).end()
#define lowbit(x) ((x) & -(x))

#define N 1007

bool a[N][N];

int f[N][N];

stack<pii> s;

int main() {
    int n = rd(), m = rd();
    for (int i = 1; i <= n; ++i)
        for (int j = 1; j <= m; ++j) {
            char c = getchar();
            while (!isalpha(c)) c = getchar();
            a[i][j] = (c == 'G');
            f[i][j] = (a[i][j] == a[i][j - 1] ? f[i][j - 1] + 1 : 1);
        }
    int ans = 0;
    for (int j = 1; j <= m; ++j) {
        for (int i = 1; i <= n; ++i) {
            int len = 0;
            while (!s.empty() && f[s.top().fr][j] >= f[i][j]) {
                len += s.top().sc;
                ans = max(ans, min(f[s.top().fr][j], len));
                s.pop();
            }
            s.push(mp(i, len + 1));
        }
        int len = 0;
        while (!s.empty()) {
            len += s.top().sc;
            ans = max(ans, min(f[s.top().fr][j], len));
            s.pop();
        }
    }
    printf("%d\n", ans * ans);
    return 0;
}