#include <bits//stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<long long, null_type, less<long long>, rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
typedef tree<long long, null_type, less_equal<long long>, rb_tree_tag,
tree_order_statistics_node_update>
ordered_multiset;
#define ll long long
#define iloop(m, h) for (auto i = m; i != h; i += (m < h ? 1 : -1))
#define jloop(m, h) for (auto j = m; j != h; j += (m < h ? 1 : -1))
#define kloop(m, h) for (auto k = m; k != h; k += (m < h ? 1 : -1))
#define lloop(m, h) for (auto l = m; l != h; l += (m < h ? 1 : -1))
#define pll pair<ll, ll>
#define INF 1000000000000000
#define MOD1 1000000007
#define MOD2 998244353
#define MOD3 1000000009
ll n, m, a[2005][2005], b[2005][2005], nm;
ll mi = INF, ma = -INF;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m;
nm = max(n, m);
iloop(0, n) jloop(0, m) {
cin >> a[i][j];
mi = min(mi, a[i][j]);
ma = max(ma, a[i][j]);
}
ll cans = INF;
lloop(0, 4) {
ll lb = 0, ub = ma - mi, mid, cptr;
bool can;
while (lb < ub) {
mid = (lb + ub) >> 1;
cptr = m;
can = 1;
iloop(0, n) {
jloop(0, cptr) if (a[i][j] > mi + mid) {cptr = j; break;}
jloop(cptr, m) if (a[i][j] < ma - mid) {can = 0; break;}
}
if (can) ub = mid;
else lb = mid + 1;
}
cans = min(cans, lb);
iloop(0, nm) jloop(i+1, nm) swap(a[i][j], a[j][i]);
iloop(0, m/2) swap(a[i], a[m-1-i]);
swap(n, m);
}
cout << cans;
}
