#include <bits/stdc++.h>
using namespace std;
int n, m, mini = 2e9, maxi = 0, a[2007][2007], sv[2007][2007];
int read(){
char p;
while((p = getchar())){
if(p < '0' || p > '9') continue;
break;
}
int ret = p - '0';
while((p = getchar())){
if(p >= '0' && p <= '9'){
ret *= 10;
ret += p - '0';
}
else break;
}
return ret;
}
bool Check(int x, int n, int m){
int cur = m, mi = 2e9, mx = 0;
bool ok = true;
for(int i = 1; i <= n; i++){
for(int j = 1; j <= cur; j++){
if(sv[i][j] - mini > x){
cur = j - 1;
break;
}
}
for(int j = cur + 1; j <= m; j++){
mi = min(mi, sv[i][j]), mx = max(mx, sv[i][j]);
}
if(mx - mi > x){
ok = false;
break;
}
}
if(ok) return true;
cur = 1, mi = 2e9, mx = 0;
for(int i = 1; i <= n; i++){
for(int j = m; j >= cur; j--){
if(sv[i][j] - mini > x){
cur = j + 1;
break;
}
}
for(int j = cur - 1; j >= 1; j--){
mi = min(mi, sv[i][j]), mx = max(mx, sv[i][j]);
}
if(mx - mi > x) return false;
}
return true;
}
bool check(int x){
for(int i = 1; i <= n; i++) for(int j = 1; j <= m; j++) sv[i][j] = a[i][j];
if(Check(x, n, m)) return true;
for(int i = 1; i <= n; i++) for(int j = 1; j <= m; j++) sv[i][j] = a[n - i + 1][j];
if(Check(x, n, m)) return true;
for(int i = 1; i <= n; i++) for(int j = 1; j <= m; j++) sv[j][i] = a[i][j];
if(Check(x, m, n)) return true;
for(int i = 1; i <= n; i++) for(int j = 1; j <= m; j++) sv[j][i] = a[i][m - j + 1];
if(Check(x, m, n)) return true;
return false;
}
int main(){
n = read(), m = read();
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++){
a[i][j] = read();
mini = min(mini, a[i][j]);
maxi = max(maxi, a[i][j]);
}
}
int l = 0, r = maxi, mid = (l + r) / 2;
while(l < r){
if(check(mid)) r = mid;
else l = mid + 1;
mid = (l + r) / 2;
}
printf("%d", mid);
}
