#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
using ii = pair<ll, ll>;
#define fastIO ios::sync_with_stdio(0); cin.tie(0);
#define fi first
#define se second
#define pb push_back
#define numBit(x) (__builtin_popcountll(1ll * (x)))
#define getBit(x, i) ((x) >> (i) & 1)
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define MASK(x) 1ll << (x)
template<class X, class Y>
bool minimize(X &x, const Y &y) {
X eps = 1e-9;
if (x > y + eps) {
x = y;
return true;
} else return false;
}
template<class X, class Y>
bool maximize(X &x, const Y &y) {
X eps = 1e-9;
if (x + eps < y) {
x = y;
return true;
} else return false;
}
const int N = 2e3 + 7, base1 = 311, base2 = 10007, MOD = 1e9 + 7;
int n, m;
ll pw[N], pw2[N], hsh[N][N];
char a[N][N];
void prepare() {
pw[0] = pw2[0] = 1;
for (int i = 1; i <= 2 * n; i++) pw[i] = pw[i - 1] * base1 % MOD;
for (int i = 1; i <= 2 * m; i++) pw2[i] = pw2[i - 1] * base2 % MOD;
for (int i = 1; i <= 2 * n; i++)
for (int j = 1; j <= 2 * m; j++) {
hsh[i][j] = (hsh[i - 1][j] * base1 % MOD + hsh[i][j - 1] * base2 % MOD) % MOD;
(hsh[i][j] -= hsh[i - 1][j - 1] * base1 * base2 % MOD + a[i][j] - 'a' + 1) %= MOD;
}
}
int get(int a, int b, int x, int y) {
ll ret = (hsh[x][y] - hsh[a - 1][y] * pw[x - a + 1] % MOD - hsh[x][b - 1] * pw2[y - b + 1] + 1ll * MOD * MOD) % MOD;
(ret += hsh[a - 1][b - 1] * pw[x - a + 1] % MOD * pw2[y - b + 1] % MOD + 1ll * MOD * MOD) %= MOD;
return ret;
}
signed main() {
fastIO;
cin >> n >> m;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
cin >> a[i][j];
a[i][j + m] = a[i][j];
a[i + n][j] = a[i][j];
a[i + n][j + m] = a[i][j];
}
}
prepare();
ii pos = {1, 1};
for (int i = 1; i <= n; i++)
for (int j = 1; j <= m; j++) {
int l = 1, r = n, ans = -1, ans1 = -1;
while (l <= r) {
int mid = l + r >> 1;
if (get(i, j, i + mid - 1, j + m - 1) == get(pos.fi, pos.se, pos.fi + mid - 1, pos.se + m - 1)) l = mid + 1;
else ans = mid, r = mid - 1;
}
if (ans == -1) continue;
l = 1, r = m;
while (l <= r) {
int mid = l + r >> 1;
if (get(i, j, i + ans - 1, j + mid - 1) == get(pos.fi, pos.se, pos.fi + ans - 1, pos.se + mid - 1)) l = mid + 1;
else ans1 = mid, r = mid - 1;
}
if (ans1 == -1) continue;
if (a[i + ans - 1][j + ans1 - 1] < a[pos.fi + ans - 1][pos.se + ans1 - 1]) pos = {i, j};
}
for (int i = pos.fi; i < pos.fi + n; i++) {
for (int j = pos.se; j < pos.se + m; j++)
cout << a[i][j];
cout << '\n';
}
}
