# include <bits/stdc++.h> using namespace std; using ll = long long; using ull = unsigned long long; const double pi = acos(-1); template<class T>constexpr T inf() { return ::std::numeric_limits<T>::max(); } template<class T>constexpr T hinf() { return inf<T>() / 2; } template <typename T_char>T_char TL(T_char cX) { return tolower(cX); } template <typename T_char>T_char TU(T_char cX) { return toupper(cX); } template<class T> bool chmin(T& a,T b) { if(a > b){a = b; return true;} return false; } template<class T> bool chmax(T& a,T b) { if(a < b){a = b; return true;} return false; } template<class T> bool is_sqare(T a) { if(floor(sqrt(a)) * floor(sqrt(a)) == a){ return true; }return false; } int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; } int d_sum(ll n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; } int d_cnt(ll n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; } ll gcd(ll a, ll b) { if (b == 0)return a; return gcd(b, a%b); }; ll lcm(ll a, ll b) { ll g = gcd(a, b); return a / g*b; }; template<class T> using dijk = priority_queue<T, vector<T>, greater<T>>; # define all(qpqpq) (qpqpq).begin(),(qpqpq).end() # define UNIQUE(wpwpw) sort(all((wpwpw)));(wpwpw).erase(unique(all((wpwpw))),(wpwpw).end()) # define LOWER(epepe) transform(all((epepe)),(epepe).begin(),TL<char>) # define UPPER(rprpr) transform(all((rprpr)),(rprpr).begin(),TU<char>) # define rep(i,upupu) for(ll i = 0, i##_len = (upupu);(i) < (i##_len);(i)++) # define reps(i,opopo) for(ll i = 1, i##_len = (opopo);(i) <= (i##_len);(i)++) # define len(x) ((int)(x).size()) # define bit(n) (1LL << (n)) # define pb push_back #ifdef LOCAL # include "_debug_print.hpp" # define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__) #else # define debug(...) (static_cast<void>(0)) #endif struct INIT{ INIT(){ std::ios::sync_with_stdio(false); std::cin.tie(0); cout << fixed << setprecision(20); } }INIT; void solve(){ int n, m; cin >> n >> m; vector<int> a(n * m), b(n * m); vector<vector<int>> vis(n, vector<int>(m, 0)); rep(i, n * m){ cin >> a[i] >> b[i]; a[i]--, b[i]--; vis[a[i]][b[i]] = i; } int ans = hinf<int>(); rep(i, n - 4)rep(j, m){ { vector<int> v; rep(k, 5)v.push_back(vis[i + k][j]); sort(all(v)); int tmp = 0; int idx_v = 0; int idx_card = 0; while(idx_v < 5 && idx_card < n * m){ int now = 5 - idx_v; if((v[idx_v] - idx_card) > now){ tmp += (v[idx_v] - idx_card - 1) / now; idx_card += (v[idx_v] - idx_card - 1) / now * now; }else if(idx_card > 0){ tmp++; } rep(k, now){ if(k + idx_card < n * m && idx_v < 5 && v[idx_v] == idx_card + k)idx_v++; } idx_card += now; if(idx_v == 5)break; } chmin(ans, tmp); } if(i == n - 5){ vector<int> v; reps(k, 4)v.push_back(vis[i + k][j]); v.push_back(vis[0][j]); sort(all(v)); int tmp = 0; int idx_v = 0; int idx_card = 0; while(idx_v < 5 && idx_card < n * m){ int now = 5 - idx_v; if((v[idx_v] - idx_card) > now){ tmp += (v[idx_v] - idx_card - 1) / now; idx_card += (v[idx_v] - idx_card - 1) / now * now; }else if(idx_card > 0){ tmp++; } rep(k, now){ if(k + idx_card < n * m && idx_v < 5 && v[idx_v] == idx_card + k)idx_v++; } idx_card += now; if(idx_v == 5)break; } chmin(ans, tmp); } } cout << ans << endl; } int main(){ int t = 1; //cin >> t; while(t--)solve(); }