#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[8]={1,0,-1,0,1,1,-1,-1};
const ll dx[8]={0,1,0,-1,1,-1,1,-1};
template <typename T> inline bool chmax(T &a, T b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
  return ((a > b) ? (a = b, true) : (false));
}
vector<vl> calc(vl &g,ll n){
  vvl ret;
  rep(i,n){
    vl cp;
    rep(j,n){
      cp.emplace_back(g[i*n+j]);
    }
    ret.emplace_back(cp);
  }
  rep(i,n){
    vl cp;
    rep(j,n){
      cp.emplace_back(g[j*n+i]);
    }
    ret.emplace_back(cp);
  }
  vl cp;
  rep(i,n)cp.emplace_back(g[i*n+i]);
  ret.emplace_back(cp);cp.clear();
  rep(i,n)cp.emplace_back(g[i*n+n-i-1]);
  ret.emplace_back(cp);cp.clear();
  return ret;
}
int main(){
  ll n,m;cin >> n >> m;
  vvl g(m,vl(n*n));
  rep(i,m){
    rep(j,n*n)cin >> g[i][j];
  }
  ll ans=INF;
  rep(i,m){
    rep(j,i){
      auto s=calc(g[i],n);
      auto t=calc(g[j],n);
      //cout << s.size() <<" " << s[0].size() << endl;
      for(auto v:s){
        for(auto w:t){
          set<ll> st;
          for(auto p:v)st.insert(p);
          for(auto q:w)st.insert(q);
          //for(auto f:st)cout << f <<" ";cout << endl;
          chmin(ans,ll(st.size()));
        }
      }
    }
  }
  cout << max(ans-1,1LL) << endl;
}