#include <iostream>
#include <vector>
#include <algorithm>
 
using namespace std;
 
int main() {
    int m, n;
    cin >> m >> n;
 
    vector<vector<int>> mat(m, vector<int>(n));
 
    // Nhập ma trận
    for (int i = 0; i < m; ++i) {
        for (int j = 0; j < n; ++j) {
            cin >> mat[i][j];
        }
    }
 
    vector<vector<int>> dp(m, vector<int>(n, 0));
    int maxSide = 0;
 
    // Tính toán dp
    for (int i = 0; i < m; ++i) {
        for (int j = 0; j < n; ++j) {
            if (i == 0 || j == 0) {
                // Nếu là hàng đầu tiên hoặc cột đầu tiên
                dp[i][j] = 1;
            } else if (mat[i][j] == mat[i-1][j] && mat[i][j] == mat[i][j-1] && mat[i][j] == mat[i-1][j-1]) {
                // Nếu có thể mở rộng hình vuông
                dp[i][j] = min({dp[i-1][j], dp[i][j-1], dp[i-1][j-1]}) + 1;
            } else {
                // Không thể mở rộng, hình vuông nhỏ nhất là 1
                dp[i][j] = 1;
            }
 
            // Cập nhật kích thước cạnh lớn nhất
            maxSide = max(maxSide, dp[i][j]);
        }
    }
 
    // Kết quả là diện tích hình vuông lớn nhất
    cout << maxSide * maxSide << endl;
 
    return 0;
}

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4 5
1 0 1 0 0
1 0 1 1 1
1 1 1 1 1
1 0 0 1 0