#include <bits/stdc++.h>

using namespace std;

const int N = 5007;

int n, m;
int dist[N];
bool vis[N];

int adj[N];
int adj2[N];
vector <int> G[N];

bool dfs(int u){
	vis[u] = true;
	for(auto t: G[u]){
		int v = adj2[t];
		if(v == 0){
			adj[u] = t;
			adj2[t] = u;
			return true;
		}
		else if(dist[v] == dist[u] + 1 && !vis[v] && dfs(v)){
			adj[u] = t;
			adj2[t] = u;
			return true;
		}
	}
	
	return false;
}

int matching(){
	bool change = true;
	while(change){
		queue <int> Q;
		for(int i = 1; i <= n; ++i)
			if(adj[i] == 0)
				Q.push(i), dist[i] = 0;
			else
				dist[i] = -1;
		
		while(!Q.empty()){
			int u = Q.front();
			Q.pop();
			
			for(auto t: G[u]){
				int v = adj2[t];
				if(v != 0 && dist[v] == -1){
					Q.push(v);
					dist[v] = dist[u] + 1;
				}
			}
		}
		
		for(int i = 1; i <= n; ++i)
			vis[i] = false;
		
		change = false;
		for(int i = 1; i <= n; ++i)
			if(adj[i] == 0 && dfs(i))
				change = true;
	}
	
	int ans = 0;
	for(int i = 1; i <= n; ++i)
		ans += adj[i] > 0;
	return ans;
}

int main(){
	scanf("%d %d", &n, &m);
	for(int i = 1; i <= m; ++i){
		int u, v;
		scanf("%d %d", &u, &v);
		G[u].push_back(v);
	}
	
	int ans = m - (2 * n - 2 - matching());
	printf("%d\n", ans);
	return 0;
}