Кунн

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <string>
#include <algorithm>
#include <string>
#include <deque>
#include <iomanip>
#include <cstddef>

#define F first
#define S second

using namespace std;


const long double eps = 0.000000005;
const long double pi = 3.1415926535897932;
const long long inf = 1e9;

vector<vector<int, int> > g;
vector<bool> used;
vector <int> d;

bool try_kuhn(int v)
{
    if (used[v])
        return false;
    used[v] = 1;
    for (int i = 0; i < g[v].size(); i++)
    {
        int to = g[v][i];
        if (d[to] == -1 || try_kuhn(d[to]))
        {
            d[to] = v;
            return true;
        }
    }
    return false;
}

int main()
{
    ios_base::sync_with_stdio(0);
    //freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);
    // freopen("slalom.in", "r", stdin);freopen("slalom.out", "w", stdout);

    int n, m;
    cin >> n >> m;
    g.resize(n);
    for (int i = 0; i < m; i++)
    {
        cin >> x >> y;
        x--;
        y--;
        g[x].push_back(y);
    }

    d.assign(n, -1);
    int ans = 0;
    for (int i = 0; i < n; i++)
    {
        used.assign(n, 0);
        ans += try_kuhn(i);
    }

    return 0;
}