import java.util.Scanner;
import java.util.Set;
import java.util.HashSet;
import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;

public class No1479 {
	
	private static class Values {
		public Set<Integer> u, v;
		public List<Integer[]> pos;
		public Values() {
			u = new HashSet<Integer>();
			v = new HashSet<Integer>();
			pos = new ArrayList<Integer[]>();
		}
	}

	private static List<Set<Integer>> edges;
	private static int[] matched;
	
	private static boolean dfs(int v, Set<Integer> visited) {
		for (int u : edges.get(v)) {
			if (visited.contains(u)) {
				continue;
			}
			visited.add(u);
			if (matched[u] == -1 || dfs(matched[u], visited)) {
				matched[u] = v;
				return true;
			}
		}
		return false;
	}
	
	private static int mpc(int xn, int yn) {
		matched = new int[yn];
		Arrays.fill(matched, -1);
		int left = xn, right = 0;
		List<Integer> ledges = new ArrayList<Integer>();
		
		for (int v = 0; v < xn ; v++) {
			if (!dfs(v, new HashSet<Integer>())) {
				left--;
				ledges.add(v);
			}
		}
		for (int v : ledges) {
			for (int u : edges.get(v)) {
				right++;
				if (matched[u] >= 0) {
					left--;
				}
			}
		}
		
		return left + right;
	}
	
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int H = scan.nextInt();
		int W = scan.nextInt();
		HashMap<Integer, Values> S = new HashMap<Integer, Values>();
		for (int i=0; i < H; i++) {
			for (int j = 0; j < W; j++) {
				int a = scan.nextInt();
				if (a == 0) {
					continue;
				}
				if (S.containsKey(a)) {
					Values v = S.get(a);
					v.u.add(i);
					v.v.add(j);
					v.pos.add(new Integer[] {i, j});
				} else {
					Values v = new Values();
					v.u.add(i);
					v.v.add(j);
					v.pos.add(new Integer[] {i, j});
					S.put(a, v);
				}
			}
		}
		scan.close();
		int cnt = 0;
		for (Values v : S.values()) {
			List<Integer> hl = new ArrayList<Integer>(v.u);
			List<Integer> wl = new ArrayList<Integer>(v.v);
			int h = hl.size();
			int w = wl.size();
			edges = new ArrayList<Set<Integer>>();
			for (int i = 0; i < h; i++) {
				edges.add(new HashSet<Integer>());
			}
			for (Integer[] i : v.pos) {
				edges.get(hl.indexOf(i[0])).add(wl.indexOf(i[1]));
			}
			cnt += mpc(h, w);
		}
		System.out.println(cnt);
	}

}