#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i,n)for (int i = 0; i < int(n); ++i)
#define rrep(i,n)for (int i = int(n)-1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template<class T> void chmax(T& a, const T& b) {a = max(a, b);}
template<class T> void chmin(T& a, const T& b) {a = min(a, b);}
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;


// https://ei1333.github.io/algorithm/bipartite-matching.html
struct Bipartite_Matching
{
  vector< vector< int > > graph;
  vector< int > match, alive, used;
  int timestamp;
 
  Bipartite_Matching(int n)
  {
    timestamp = 0;
    graph.resize(n);
    alive.assign(n, 1);
    used.assign(n, 0);
    match.assign(n, -1);
  }
 
  void add_edge(int u, int v)
  {
    graph[u].push_back(v);
    graph[v].push_back(u);
  }
 
  bool dfs(int v)
  {
    used[v] = timestamp;
    for(int i = 0; i < graph[v].size(); i++) {
      int u = graph[v][i], w = match[u];
      if(alive[u] == 0) continue;
      if(w == -1 || (used[w] != timestamp && dfs(w))) {
        match[v] = u;
        match[u] = v;
        return (true);
      }
    }
    return (false);
  }
 
  int bipartite_matching()
  {
    int ret = 0;
    for(int i = 0; i < graph.size(); i++) {
      if(alive[i] == 0) continue;
      if(match[i] == -1) {
        ++timestamp;
        ret += dfs(i);
      }
    }
    return (ret);
  } 
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int h, w;
    cin >> h >> w;
    vector<vector<P>> d(500001);
    rep(i, h) rep(j, w) {
        int a;
        cin >> a;
        if (a) d[a].emplace_back(i, j);
    }
    int ans = 0;
    for(auto& ps: d) if (!ps.empty()) {
        Bipartite_Matching bm(h + w);
        for(auto [i, j]: ps) {
            bm.add_edge(i, h + j);
        }
        ans += bm.bipartite_matching();
    }
    cout << ans << '\n';
}