// #includes {{{
#include <algorithm>
#include <numeric>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <list>
#include <deque>
#include <stack>
#include <vector>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cassert>
#include <cstring>
#include <cmath>
using namespace std;
// }}}
// pre-written code {{{
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define RREP(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define FOR(i,c) for(__typeof((c).begin()) i=(c).begin();i!=(c).end();++i)
#define LET(x,a) __typeof(a) x(a)
//#define IFOR(i,it,c) for(__typeof((c).begin())it=(c).begin();it!=(c).end();++it,++i)
#define ALL(c) (c).begin(), (c).end()
#define MP make_pair

#define EXIST(e,s) ((s).find(e)!=(s).end())

#define REvector(a) memvector((a),0,sizeof(a))
#define vector(a) memvector((a),-1,sizeof(a))
#define PB push_back
#define DEC(it,command) __typeof(command) it=command

const int INF=0x3f3f3f3f;

typedef long long Int;
typedef unsigned long long uInt;
#ifdef __MINGW32__
typedef double rn;
#else
typedef long double rn;
#endif

typedef pair<int,int> pii;

/*
#ifdef MYDEBUG
#include"debug.h"
#include"print.h"
#endif
*/
// }}}

int C[222][111][111];
vector<vector<vector<int> > > v;

int N,M;

vector<vector<int> > make_blist(int s){
	vector<vector<int> > bs;
	REP(i,N){
		vector<int> st;
		REP(j,N)st.push_back(C[s][i][j]);
		bs.push_back(st);
	}
	REP(j,N){
		vector<int> st;
		REP(i,N)st.push_back(C[s][i][j]);
		bs.push_back(st);
	}
	{
		vector<int> st;
		REP(i,N)st.push_back(C[s][i][i]);
		bs.push_back(st);
	}
	{
		vector<int> st;
		REP(i,N)st.push_back(C[s][i][N-1-i]);
		bs.push_back(st);
	}
	return bs;
}

int main(){
	cin>>N>>M;
	REP(t,M)REP(i,N)REP(j,N)cin>>C[t][i][j];
	REP(t,M){
		v.push_back(make_blist(t));
	}
	int ans = INF;
	REP(t,M)RREP(s,t+1,M){
		for(auto a:v[t])for(auto b:v[s]){
			vector<int> c = a;
			c.insert(c.end(),ALL(b));
			sort(ALL(c));
			int k = distance(c.begin(),unique(ALL(c)));
			ans = min(k,ans);
		}
	}
	cout<<max(1,ans-1)<<endl;
	return 0;
}