#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long
// 217
// 44
using namespace std;
const int INF = 1e9;
const int MAXN = 2000;
int mat[MAXN + 1][MAXN + 1], aux[MAXN + 1][MAXN + 1];
int n, m, mn, mx;
inline void rot() {
int i, j;
for(i = 1; i <= m; i++) {
for(j = 1; j <= n; j++) {
aux[i][j] = mat[n - j + 1][i];
}
}
swap(n, m);
for(i = 1; i <= n; i++) {
for(j = 1; j <= m; j++) {
mat[i][j] = aux[i][j];
}
}
}
inline bool solve(int dif) {
int l = INF, r = -INF;
int last = 1;
for(int j = 1; j <= m; j++) {
int i = n;
while(i >= max(1, last) && mat[i][j] <= mn + dif) {
i--;
}
last = max(last, i + 1);
while(i >= 1) {
l = min(l, mat[i][j]);
r = max(r, mat[i][j]);
if(r - l > dif) {
return 0;
}
i--;
}
}
return r - l <= dif;
}
int main() {
//ifstream cin("A.in");
//ofstream cout("A.out");
int i, j;
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
cin >> n >> m;
mx = -INF, mn = INF;
for(i = 1; i <= n; i++) {
for(j = 1; j <= m; j++) {
cin >> mat[i][j];
mn = min(mn, mat[i][j]);
mx = max(mx, mat[i][j]);
}
}
int ans = INF;
for(i = 0; i < 4; i++) {
int res = -1;
for(int step = 1 << 29; step; step >>= 1) {
if(res + step <= mx - mn && solve(res + step) == 0) {
res += step;
}
}
ans = min(ans, res + 1);
if(i < 3) {
rot();
}
}
cout << ans;
//cin.close();
//cout.close();
return 0;
}
