#include <bits/stdc++.h>

using namespace std;
void fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
}

int main() {
    fast_io();
    int n, m;
    cin >> n >> m;
    vector<int> deg_i(n), deg_o(n);
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        deg_i[v - 1]++;
        deg_o[u - 1]++;
    }
    vector<int> diff(n);
    for (int i = 0; i < n; i++) {
        diff[i] = deg_i[i] - deg_o[i];
    }
    sort(diff.begin(), diff.end());
    long long ans_full = 0;
    for (int i = 0; i < n; i++) {
        ans_full += abs(diff[i]);
    }
    long long ans_semi = abs(diff[0] + 1) + abs(diff[n - 1] - 1);
    for (int i = 1; i < n - 1; i++) {
        ans_semi += abs(diff[i]);
    }
    cout << min(ans_full, ans_semi) / 2 << endl;
}