#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, x, n) for(int i = x; i <= n; i++)
#define rep3(i, x, n) for(int i = x; i >= n; i--)
#define each(e, v) for(auto &e: v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
const int MOD = 1000000007;
//const int MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
template<typename T> bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;};
template<typename T> bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;};

struct io_setup{
    io_setup(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

struct Bipartite_Matching{
    vector<vector<int>> es;
    vector<int> d, match;
    vector<bool> used, used2;
    const int n, m;

    Bipartite_Matching(int n, int m) : es(n), d(n), match(m), used(n), used2(n), n(n), m(m) {}

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

    void _bfs(){
        fill(begin(d), end(d), -1);
        queue<int> que;
        for(int i = 0; i < n; i++){
            if(!used[i]) que.emplace(i), d[i] = 0;
        }
        while(!que.empty()){
            int i = que.front(); que.pop();
            for(auto &e: es[i]){
                int j = match[e];
                if(j != -1 && d[j] == -1){
                    que.emplace(j), d[j] = d[i]+1;
                }
            }
        }
    }

    bool _dfs(int now){
        used2[now] = true;
        for(auto &e: es[now]){
            int u = match[e];
            if(u == -1 || (!used2[u] && d[u] == d[now]+1 && _dfs(u))){
                match[e] = now, used[now] = true;
                return true;
            }
        }
        return false;
    }

    int bipartite_matching(){
        fill(begin(match), end(match), -1), fill(begin(used), end(used), false);
        int ret = 0;
        while(true){
            _bfs();
            fill(begin(used2), end(used2), false);
            int flow = 0;
            for(int i = 0; i < n; i++){
                if(!used[i] && _dfs(i)) flow++;
            }
            if(flow == 0) break;
            ret += flow;
        }
        return ret;
    }
};

int main(){
    int H, W; cin >> H >> W;

    vector<vector<int>> A(H, vector<int>(W));
    rep(i, H){
        rep(j, W){
            cin >> A[i][j];
        }
    }

    int MAX = 500000;

    vector<vector<pii>> ps(MAX+1);

    rep(i, H){
        rep(j, W){
            ps[A[i][j]].eb(i, j);
        }
    }

    vector<int> cx(H, 0), cy(W, 0);
    int sx = 0, sy = 0;

    ll ans = 0;
    Bipartite_Matching G(H, W); 

    rep3(i, MAX, 1){
        if(ps[i].empty()) continue;

        each(e, ps[i]){
            auto [x, y] = e;
            G.add_edge(x, y);
        }

        ans += G.bipartite_matching();

        rep(i, H) G.es[i].clear();
    }

    cout << ans << '\n';
}