// author : daohuyenchi



#include <bits/stdc++.h>

using namespace std;

#define ull unsigned long long
#define db double
#define i32 int32_t  
#define i64 int64_t 
#define ll long long
// 
#define fi first
#define se second


//                                      #define int long long    // consider carefully


//
#define pii pair<int, int>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define pil pair<int, ll> 
#define PAIR make_pair 
//                                      TIME IS LIMITED ...  
#define  rep(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define repd(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define repv(v, H) for(auto &v: H)
//                                      REFLECT ON THE PAST ...
#define RESET(c, x) memset(c, x, sizeof(c))
#define MASK(i) (1LL << (i))
#define BIT(mask, i) (((mask) >> (i)) & 1LL)
#define ONBIT(mask, i) ((mask) | (1LL << (i)))
#define OFFBIT(mask, i) ((mask) &~ (1LL << (i)))
#define COUNTBIT __builtin_popcountll
//                                      30 / 1 / 2024 ? love is zero... start from zero 
#define PB push_back
#define EB emplace_back
#define vi vector<int>
#define vll vector<ll>
#define lwb lower_bound
#define upb upper_bound
#define all(v) (v).begin(), (v).end()
#define special(H) (H).resize(distance(H.begin(), unique(all(H))))
//                                      
#define sp ' ' 
#define nl '\n'
#define yes "YES"
#define no "NO"
#define Log2(n) (63 - __builtin_clzll(n))
#define left __left__
#define right __right__ 

//____________________________________________________________________


template <class X, class Y> bool maximize(X &a, const Y &b) {
    if(a < b) return a = b, true;
    return false;
}

template <class X, class Y> bool minimize(X &a, const Y &b) {
    if(a > b) return a = b, true;
    return false;
}

const int MOD      = 1000000007;
// const int MOD[2] = {1000000009, 998244353};

template<class X> void modmize(X &x, int cur_Mod = MOD) {
    if(x >= cur_Mod) x -= cur_Mod;
    if(x < 0) x += cur_Mod;
}

template <class... T>
void print(T&&... n) {
    using exp = int[];
    exp{0, (cerr << n << sp, 0)...};
    cerr << endl;
}

template <class T, class... C>
void assign(int n, T v, C&&... a) {
    using e = int[];
    e{(a.assign(n, v), 0)...};
}

template <class... C>
void resize(int n, C&&... a) {
    using e = int[];
    e{(a.resize(n), 0)...};
}

template <class T>
using vector2d = vector<vector<T>>;
template <class T>
using vector3d = vector<vector2d<T>>;

template <class T> int ssize(T &a) { return (int) a.size(); }


//____________________________________________________________________


mt19937 rng(chrono::steady_clock().now().time_since_epoch().count());

const long long oo = 1e18 + 7;
const int INF      = 2e9;
const int nmax     = 2e5 + 10;
const int MAX      = 2e5;
const int base     = 311;
const db eps       = 1e-6;
const int block    = 500;
static const double PI = acos(-1.0);

//____________________________________________________________________


int n, m;
vector2d<int> a;
vector2d<int> fd, fu, fl, fr;

namespace subtask1 {

    struct HuyenChi {

        vector<int> st;

        void Init(int _n) {
            assign(_n * 4 + 5, INF, st);
        }

        void upd(int id, int l, int r, int i, int val) {
            if(l > i || r < i) return;
            if(l == r) {
                minimize(st[id], val);
                return;
            }
            int mid = (l + r) / 2;
            upd(id * 2, l, mid, i, val);
            upd(id * 2 + 1, mid + 1, r, i, val);
            st[id] = min(st[id * 2], st[id * 2 + 1]);
        }

        int walk(int id, int l, int r, int val) {
            if(l == r) return (st[id] <= val ? l : INF);
            int mid = (l + r) / 2;
            if(st[id * 2 + 1] <= val) return walk(id * 2 + 1, mid + 1, r, val);
            return walk(id * 2, l, mid, val);
        }

        int calc(int id, int l, int r, int u, int v, int val) {
            if(l > v || r < u || st[id] > val) return INF;
            if(u <= l && r <= v) {
                if(st[id] <= val) return walk(id, l, r, val);
                else return INF;
            }
            int mid = (l + r) >> 1;
            if(v <= mid) return calc(id * 2, l, mid, u, v, val);
            else if(u > mid) return calc(id * 2 + 1, mid + 1, r, u, v, val);
            int cur = calc(id * 2 + 1, mid + 1, r, u, v, val);
            if(cur < INF) return cur;
            return calc(id * 2, l, mid, u, v, val);
        } 

    } ;

    void SOLVE() {

        HuyenChi chi;

        vector2d<pii> List(2 * m + 1, vector<pii>());

        rep(i, 1, n) {
            rep(j, 1, m) {
                if(a[i][j] == 0) continue;
                List[i - j + m].push_back({i, j});
            }
        }

        int ans = 0;
        rep(_i, 0, m + m) {
            if(List[_i].empty() == 0) {
                chi.Init(n);

                auto &g = List[_i];
                sort(all(List[_i]));

                repd(i, ssize(g) - 1, 0) {
                    int x = g[i].fi;
                    int y = g[i].se;
                    if(a[x][y] == 0) continue;

                    int v2 = min(fl[x][y], fu[x][y]);
                    chi.upd(1, 1, n, x, x - v2);
                    
                    int v = min(fr[x][y], fd[x][y]);
                    int x2 = chi.calc(1, 1, n, x, x + v - 1, x - 1);
                    if(x2 != INF) {
                        maximize(ans, x2 - x + 1);

                    }

                }
            }
        }

        cout << 1ll * ans * ans << nl;

    }

}

int rnd(int l, int r) {
    return uniform_int_distribution<int> (l, r) (rng);
}

void tintingyn() {

    cin >> n >> m;

    // n = 1e3; m = 1e3;

    assign(n + 2, vector<int>(m + 2, 0), a);
    rep(i, 1, n) {
        rep(j, 1, m) {
            cin >> a[i][j];
            // a[i][j] = rnd(0, 1);
        }
    }

    assign(n + 2, vector<int>(m + 2, 0), fd, fu, fl, fr);

    rep(i, 1, n) {
        fl[i][1] = 1;
        rep(j, 2, m) {
            if(a[i][j] != a[i][j - 1]) fl[i][j] = 1;
            else fl[i][j] = fl[i][j - 1] + 1;
        }
        fr[i][m] = 1;
        repd(j, m - 1, 1) {
            if(a[i][j] != a[i][j + 1]) fr[i][j] = 1;
            else fr[i][j] = fr[i][j + 1] + 1;
        }
    }

    rep(j, 1, m) {
        fu[1][j] = 1;
        rep(i, 2, n) {
            if(a[i][j] != a[i - 1][j]) fu[i][j] = 1;
            else fu[i][j] = fu[i - 1][j] + 1;
        }

        fd[n][j] = 1;
        repd(i, n - 1, 1) {
            if(a[i][j] != a[i + 1][j]) fd[i][j] = 1;
            else fd[i][j] = fd[i + 1][j] + 1;
        }
    }

    subtask1:: SOLVE();



}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    //________________________________________________________________

    #define TASK "MSQUARE"
    if(fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }

    //________________________________________________________________
    
    //  CODE FROM HERE ...! 





    int num_test = 1; 
    // cin >> num_test;

    while(num_test--) {

        tintingyn();

    }


    cerr << '\n' << "Time elapsed: " << (1.0 * clock() / CLOCKS_PER_SEC) << " s\n" << nl;

    return 0;
}