#include <bits/stdc++.h>
//#include <atcoder/all>
//using namespace atcoder;
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
 
using namespace std;
 
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef pair<int, int> pii;
typedef pair<long long, long long> PLL;
typedef pair<int, PII> TIII;
 
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
 
 
#define FOR(i, s, n) for (int i = s; i < (int)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto &a : x)
#define all(x) x.begin(), x.end()
 
#define MOD 1000000007
 
template<class T1, class T2> inline bool chmax(T1 &a, T2 b) {if (a < b) {a = b; return true;} return false;}
template<class T1, class T2> inline bool chmin(T1 &a, T2 b) {if (a > b) {a = b; return true;} return false;}
const double EPS = 1e-12, PI = acos(-1);
const double pi = 3.141592653589793238462643383279;
//ここから編集    
typedef string::const_iterator State;
ll GCD(ll a, ll b){
  return (b==0)?a:GCD(b, a%b);
}
ll LCM(ll a, ll b){
  return a/GCD(a, b) * b;
}
template< int mod >
struct ModInt {
  int x;
 
  ModInt() : x(0) {}
 
  ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
 
  ModInt &operator+=(const ModInt &p) {
    if((x += p.x) >= mod) x -= mod;
    return *this;
  }
 
  ModInt &operator-=(const ModInt &p) {
    if((x += mod - p.x) >= mod) x -= mod;
    return *this;
  }
 
  ModInt &operator*=(const ModInt &p) {
    x = (int) (1LL * x * p.x % mod);
    return *this;
  }
 
  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }
 
  ModInt operator-() const { return ModInt(-x); }
 
  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
 
  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
 
  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
 
  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
 
  bool operator==(const ModInt &p) const { return x == p.x; }
 
  bool operator!=(const ModInt &p) const { return x != p.x; }
 
  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while(b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }
 
  ModInt pow(int64_t n) const {
    ModInt ret(1), mul(x);
    while(n > 0) {
      if(n & 1) ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }
 
  friend ostream &operator<<(ostream &os, const ModInt &p) {
    return os << p.x;
  }
 
  friend istream &operator>>(istream &is, ModInt &a) {
    int64_t t;
    is >> t;
    a = ModInt< mod >(t);
    return (is);
  }
 
  static int get_mod() { return mod; }
};
 
using modint = ModInt< 998244353 >;
template< typename T >
struct Combination {
  vector< T > _fact, _rfact, _inv;
 
  Combination(int sz) : _fact(sz + 1), _rfact(sz + 1), _inv(sz + 1) {
    _fact[0] = _rfact[sz] = _inv[0] = 1;
    for(int i = 1; i <= sz; i++) _fact[i] = _fact[i - 1] * i;
    _rfact[sz] /= _fact[sz];
    for(int i = sz - 1; i >= 0; i--) _rfact[i] = _rfact[i + 1] * (i + 1);
    for(int i = 1; i <= sz; i++) _inv[i] = _rfact[i] * _fact[i - 1];
  }
 
  inline T fact(int k) const { return _fact[k]; }
 
  inline T rfact(int k) const { return _rfact[k]; }
 
  inline T inv(int k) const { return _inv[k]; }
 
  T P(int n, int r) const {
    if(r < 0 || n < r) return 0;
    return fact(n) * rfact(n - r);
  }
 
  T C(int p, int q) const {
    if(q < 0 || p < q) return 0;
    return fact(p) * rfact(q) * rfact(p - q);
  }
 
  T H(int n, int r) const {
    if(n < 0 || r < 0) return (0);
    return r == 0 ? 1 : C(n + r - 1, r);
  }
};
 
ll modpow(ll x, ll n, ll mod) {
  ll res = 1;
  while(n) {
    if(n&1) res = (res * x) % mod;
    x = (x * x) % mod;
    n >>= 1;
  }
  return res;
} 
inline long long mod(long long a, long long m) {
    return (a % m + m) % m;
}
struct HopcroftKarp {
  vector< vector< int > > graph;
  vector< int > dist, match;
  vector< bool > used, vv;

  HopcroftKarp(int n, int m) : graph(n), match(m, -1), used(n) {}

  void add_edge(int u, int v) {
    graph[u].push_back(v);
  }

  void bfs() {
    dist.assign(graph.size(), -1);
    queue< int > que;
    for(int i = 0; i < graph.size(); i++) {
      if(!used[i]) {
        que.emplace(i);
        dist[i] = 0;
      }
    }

    while(!que.empty()) {
      int a = que.front();
      que.pop();
      for(auto &b : graph[a]) {
        int c = match[b];
        if(c >= 0 && dist[c] == -1) {
          dist[c] = dist[a] + 1;
          que.emplace(c);
        }
      }
    }
  }

  bool dfs(int a) {
    vv[a] = true;
    for(auto &b : graph[a]) {
      int c = match[b];
      if(c < 0 || (!vv[c] && dist[c] == dist[a] + 1 && dfs(c))) {
        match[b] = a;
        used[a] = true;
        return (true);
      }
    }
    return (false);
  }

  int bipartite_matching() {
    int ret = 0;
    while(true) {
      bfs();
      vv.assign(graph.size(), false);
      int flow = 0;
      for(int i = 0; i < graph.size(); i++) {
        if(!used[i] && dfs(i)) ++flow;
      }
      if(flow == 0) return (ret);
      ret += flow;
    }
  }

  void output() {
    for(int i = 0; i < match.size(); i++) {
      if(~match[i]) {
        cout << match[i] << "-" << i << endl;
      }
    }
  }
};
int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(20);

  int H, W; cin >> H >> W;
  vector<vector<int>> a(H, vector<int>(W,0));
  REP(i,H) REP(j,W) cin >> a[i][j];

  vector<int> v;
  v.push_back(0);
  REP(i,H) REP(j,W) v.push_back(a[i][j]);
  sort(all(v));
  v.erase(unique(all(v)), v.end());

  REP(i,H) REP(j,W) a[i][j] = lower_bound(all(v), a[i][j]) - v.begin();

  vector<vector<int>> g(v.size());
  REP(i,H) REP(j,W) {
    g[a[i][j]].push_back(i*W+j);
  }
  int ans = 0;
  for(int i=1; i<v.size(); i++) {
    HopcroftKarp bm(H, W);
    for(int j=0; j<g[i].size(); j++) {
      int y = g[i][j]/W, x = g[i][j]%W;
      bm.add_edge(y, x);
    }
    ans += bm.bipartite_matching();
  }
  cout << ans << endl;
  return 0;
}