#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
istream &operator>>(istream &is, modint &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint &a) { return os << a.val(); }
istream &operator>>(istream &is, modint998244353 &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint998244353 &a) { return os << a.val(); }
istream &operator>>(istream &is, modint1000000007 &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint1000000007 &a) { return os << a.val(); } 

typedef long long ll;
typedef vector<vector<int>> Graph;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define rep(i,n) for (int i = 0;i < (int)(n); i++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define my_sort(x) sort(x.begin(), x.end())
#define my_max(x) *max_element(all(x))
#define my_min(x) *min_element(all(x))
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const int INF = (1<<30) - 1;
const ll LINF = (1LL<<62) - 1;
const int MOD = 998244353;
const int MOD2 = 1e9+7;
const double PI = acos(-1);
vector<int> di = {1,0,-1,0};
vector<int> dj = {0,1,0,-1};

#ifdef LOCAL
#  include <debug_print.hpp>
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

int main(){
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    int N,M; cin >> N >> M;
    int V = N * M;
    vector<int> n(V), m(V);
    rep(i,V) {
        cin >> n[i] >> m[i];
        n[i]--;
        m[i]--;
    }
    vector<int> idx(V);
    rep(i,V) idx[n[i] + N * m[i]] = i + 1;
    int ans = INF;
    for(int x=0;x<V;x++){
        int sign = x / N;
        int num = x % N;
        if (1 <= num && num < 4) continue;
        vector<int> check_idx;
        if (num == 0){
            check_idx.push_back(idx[N * sign + 0]);
            check_idx.push_back(idx[N * sign + N - 1]);
            check_idx.push_back(idx[N * sign + N - 2]);
            check_idx.push_back(idx[N * sign + N - 3]);
            check_idx.push_back(idx[N * sign + N - 4]);
        }
        else{
            check_idx.push_back(idx[N * sign + num]);
            check_idx.push_back(idx[N * sign + num - 1]);
            check_idx.push_back(idx[N * sign + num - 2]);
            check_idx.push_back(idx[N * sign + num - 3]);
            check_idx.push_back(idx[N * sign + num - 4]);
        }
        sort(all(check_idx));
        int tmp = 0;
        int now = 5;
        int cnt = 0;
        for(int i=0;i<5;i++)if(check_idx[i]<=5)cnt++;
        debug(check_idx);
        while(cnt < 5){
            int a = (check_idx[cnt] + (5 - cnt) - 1) / (5 - cnt);
            tmp += (min((5 - cnt) * a, V) - now) / (5 - cnt);
            debug(cnt, a, now, tmp, x);
            now = min((5 - cnt) * a, V);
            while(cnt < 5){
                if(check_idx[cnt] <= now)cnt++;
                else break;
                debug(cnt, a, now, tmp, x);
            }
        }
        chmin(ans, tmp);
    }
    cout << ans << endl;
}