#include "bits/stdc++.h"
using namespace std;
#ifdef Nero
#include "Deb.h"
#else
#define deb(...)
#endif
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m;
cin >> n >> m;
int mx = 0;
vector<vector<int>> a(n, vector<int> (m));
for (int i = 0; i < n; ++i) {
for (int j = 0; j < m; ++j) {
cin >> a[i][j];
mx = max(mx, a[i][j]);
}
}
auto check = [&](int mid) {
int la = m - 1;
int min_val = mx - mid;
vector<vector<bool>> region(n, vector<bool> (m));
for (int i = 0; i < n; ++i) {
for (int j = 0; j <= la; ++j) {//coli <= coli-1
if (a[i][j] < min_val) {
la = j - 1;
break;
}
region[i][j] = 1;
}
}
vector<int> bmx(2), bmn(2, 1e9);
for (int i = 0; i < n; ++i) {
for (int j = 0; j < m; ++j) {
bmx[region[i][j]] = max(bmx[region[i][j]], a[i][j]);
bmn[region[i][j]] = min(bmn[region[i][j]], a[i][j]);
}
}
return max(bmx[0] - bmn[0], bmx[1] - bmn[1]) <= mid;
};
auto solve = [&]() {
int l = 0, r = 1e9;
while (l < r) {
int mid = (l + r) >> 1;
if (check(mid)) {
r = mid;
} else {
l = mid + 1;
}
}
return l;
};
auto flip_rows = [&]() {
for (int i = 0; i < n / 2; ++i) {
for (int j = 0; j < m; ++j) {
swap(a[i][j], a[n - i - 1][j]);
}
}
};
auto flip_cols = [&]() {
for (int i = 0; i < n; ++i) {
for (int j = 0; j < m / 2; ++j) {
swap(a[i][j], a[i][m - j - 1]);
}
}
};
int ans = solve(); //0, 0
flip_cols();
ans = min(ans, solve()); //0, 1
flip_rows();
ans = min(ans, solve()); //1, 1
flip_cols();
ans = min(ans, solve());//1, 0
cout << ans << '\n';
return 0;
}
