#include <bits/stdc++.h>
using namespace std;
int main()
{
int N, M;
cin >> N >> M;
int high = 0, low = 1000000000;
vector<vector<int>> Tab(N, vector<int>(M));
for (int i = 0; i < N; i++)
{
for (int j = 0; j < M; j++)
{
cin >> Tab[i][j];
high = max(high, Tab[i][j]);
low = min(low, Tab[i][j]);
}
}
vector<vector<int>> colmin(N, vector<int>(M)), colmax(N, vector<int>(M)), rowminlr(N, vector<int>(M)), rowminrl(N, vector<int>(M)), rowmaxlr(N, vector<int>(M)), rowmaxrl(N, vector<int>(M));
for (int i = 0; i < M; i++)
{
colmin[N - 1][i] = Tab[N - 1][i];
colmax[N - 1][i] = Tab[N - 1][i];
}
for (int i = N - 2; i >= 0; i--)
{
for (int j = 0; j < M; j++)
{
colmin[i][j] = min(colmin[i + 1][j], Tab[i][j]);
colmax[i][j] = max(colmax[i + 1][j], Tab[i][j]);
}
}
for (int i = 0; i < N; i++)
{
rowminlr[i][0] = Tab[i][0];
rowmaxlr[i][0] = Tab[i][0];
rowminrl[i][M - 1] = Tab[i][M - 1];
rowmaxrl[i][M - 1] = Tab[i][M - 1];
}
for (int j = 1; j < M; j++)
{
for (int i = 0; i < N; i++)
{
rowminlr[i][j] = min(rowminlr[i][j - 1], Tab[i][j]);
rowmaxlr[i][j] = max(rowmaxlr[i][j - 1], Tab[i][j]);
}
}
for (int j = M - 2; j >= 0; j--)
{
for (int i = 0; i < N; i++)
{
rowminrl[i][j] = min(rowminrl[i][j + 1], Tab[i][j]);
rowmaxrl[i][j] = max(rowmaxrl[i][j + 1], Tab[i][j]);
}
}
int best = 1234567890;
int maxx = 0, minn = 1000000000;
int x = 0, y = M - 1;
while (x < N && y >= 0)
{
int a = min(minn, rowminlr[x][y]);
int b = max(maxx, colmax[x][y]);
if (high - a > b - low)
{
maxx = b;
y--;
}
else
{
minn = a;
x++;
}
}
best = min(best, max(high - minn, maxx - low));
maxx = 0, minn = 1000000000;
x = 0, y = M - 1;
while (x < N && y >= 0)
{
int a = min(minn, colmin[x][y]);
int b = max(maxx, rowmaxlr[x][y]);
if (high - a > b - low)
{
maxx = b;
x++;
}
else
{
minn = a;
y--;
}
}
best = min(best, max(high - minn, maxx - low));
maxx = 0, minn = 1000000000;
x = 0, y = 0;
while (x < N && y < M)
{
int a = min(minn, rowminrl[x][y]);
int b = max(maxx, colmax[x][y]);
if (high - a > b - low)
{
maxx = b;
y++;
}
else
{
minn = a;
x++;
}
}
best = min(best, max(high - minn, maxx - low));
maxx = 0, minn = 1000000000;
x = 0, y = 0;
while (x < N && y < M)
{
int a = min(minn, colmin[x][y]);
int b = max(maxx, rowmaxrl[x][y]);
if (high - a > b - low)
{
maxx = b;
x++;
}
else
{
minn = a;
y++;
}
}
best = min(best, max(high - minn, maxx - low));
cout << best;
}
