#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1e9 + 10;
const ll INFL = 4e18;

#include <atcoder/maxflow>
using namespace atcoder;

const int MX = 5e5 + 5;

int main() {
    int H, W;
    cin >> H >> W;
    vector<vector<int>> A(H, vector<int>(W));
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            cin >> A[i][j];
        }
    }

    vector<vector<pair<int, int>>> P(MX);
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            P[A[i][j]].push_back({i, j});
        }
    }

    int ans = 0;
    for (int i = 1; i < MX; i++) {
        if (!P[i].empty()) {
            mf_graph<ll> mf(H + W + 2);
            for (auto [x, y] : P[i]) {
                mf.add_edge(x, H + y, 1);
            }
            for (int j = 0; j < H; j++) {
                mf.add_edge(H + W, j, 1);
            }
            for (int j = 0; j < W; j++) {
                mf.add_edge(H + j, H + W + 1, 1);
            }
            ans += mf.flow(H + W, H + W + 1);
        }
    }

    cout << ans << endl;
}