//https://www.instagram.com/_modwwe/
#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2")
#include<bits/stdc++.h>
//#define int long long
//#define ll long long
#define down cout<<'\n';
#define debug cout<<" cucuucucuuu",down
#define NHP ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
#define modwwe int t;cin>>t; while(t--)
#define bit(i,j) (i>>j&1)
#define sobit(a) __builtin_popcountll(a)
#define task "test"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".out","w",stdout)
#define pb push_back
#define checktime cerr << (double)clock() / CLOCKS_PER_SEC * 1000 << " ms";
using namespace std;
void phongbeo();
const int inf=1e18;
const int mod2=1e9+7;
const int mod1=998244353;
struct icd
{
int a,b;
};
struct ib
{
int a;
int b;
};
struct ic
{
int a,b,c;
};
struct id
{
int a,b,c,d;
};
struct ie
{
int a,b,c,d,e,f;
};
int n,m,s1,s2,s4,s3,sf,k,r,mid,s5,s6,mx,s7,s8,s9,mx2,res,dem2=0,dem=0,l;
int i,s10,s12;
int kk;
int el=29;
main()
{
#ifndef ONLINE_JUDGE
///fin(task),fou(task);
#endif
NHP
/// cin>>s1;
// modwwe
phongbeo();
}
int a[2001][2001];
int d[2002];
int b[2001];
int c[2001];
bool solve1(int x)
{
s3=0;
s4=0;
for(int i=1; i<=m; i++)
{
s3=max(s3,b[i]);
for(int j=1; j<=s3; j++)
s4=max(s4,a[j][i]);
d[i]=s3;
}
if(s4-s2>x) return 0;
d[m+1]=n;
s7=1e9;
for(int i=m; i>=1; --i)
{
while(d[i]<d[i+1]&&a[d[i]+1][i]-s2<=x) d[i]++;
for(int j=d[i]+1; j<=n; j++)
s7=min(s7,a[j][i]);
}
return s5-s7<=x;
}
bool solve3(int x)
{
s3=0;
s4=0;
for(int i=m; i>=1; i--)
{
s3=max(s3,b[i]);
for(int j=1; j<=s3; j++)
s4=max(s4,a[j][i]);
d[i]=s3;
}
if(s4-s2>x) return 0;
d[m+1]=n;
d[0]=n;
s7=1e9;
for(int i=1; i<=m; ++i)
{
while(d[i]<d[i-1]&&a[d[i]+1][i]-s2<=x) d[i]++;
for(int j=d[i]+1; j<=n; j++)
s7=min(s7,a[j][i]);
}
return s5-s7<=x;
}
bool solve4(int x)
{
s3=0;
s4=1e9;
for(int i=m; i>=1; i--)
{
s3=max(s3,c[i]);
for(int j=1; j<=s3; j++)
s4=min(s4,a[j][i]);
d[i]=s3;
}
if(s5-s4>x) return 0;
d[m+1]=n;
s7=0;
d[0]=n;
for(int i=1; i<=m; ++i)
{
while(d[i]<d[i-1]&&s5-a[d[i]+1][i]<=x) d[i]++;
for(int j=d[i]+1; j<=n; j++)
s7=max(s7,a[j][i]);
}
return s7-s2<=x;
}
bool solve2(int x)
{
s3=0;
s4=1e9;
for(int i=1; i<=m; i++)
{
s3=max(s3,c[i]);
for(int j=1; j<=s3; j++)
s4=min(s4,a[j][i]);
d[i]=s3;
}
if(s5-s4>x) return 0;
d[m+1]=n;
s7=0;
for(int i=m; i>=1; --i)
{
while(d[i]<d[i+1]&&s5-a[d[i]+1][i]<=x) d[i]++;
for(int j=d[i]+1; j<=n; j++)
s7=max(s7,a[j][i]);
}
return s7-s2<=x;
}
bool check(int x)
{
return (((solve1(x)|solve2(x))|solve3(x))|solve4(x));
}
void phongbeo()
{
cin>>n>>m;
s2=1e9;
for(int i=1; i<=n; i++)
for(int j=1; j<=m; j++)
cin>>a[i][j],s2=min(s2,a[i][j]),s3=max(s3,a[i][j]);
for(int j=1; j<=m; j++)
for(int i=1; i<=n; i++)
{
if(a[i][j]==s2)
b[j]=i;
if(a[i][j]==s3)
c[j]=i;
}
s5=s3;
s6=s2;
l=1;
r=1e9;
while(l<=r)
{
int mid=l+r>>1;
if(check(mid))r=mid-1;
else l=mid+1;
}
cout<<r+1;
}
