#include <algorithm>
#include <bit>
#include <bitset>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <deque>
#include <iostream>
#include <map>
#include <random>
#include <unordered_set>
#include <unordered_map>
#include <vector>
#include <set>
#include <string>

using namespace::std;

template<typename T, typename U>
ostream& operator<< (ostream& o, const pair<T, U>& p) {
  o << "<" << p.first << ", " << p.second << ">";
  return o;
}

template <typename T>
ostream& operator<< (ostream& o, const vector<T>& v) {
 for (const auto& x : v) o << x << " ";
 return o;
}

template <typename T>
ostream& operator<< (ostream& o, const set<T>& v) {
 for (const auto& x : v) o << x << " ";
 return o;
}

template <typename T>
ostream& operator<< (ostream& o, const deque<T>& v) {
 for (const auto& x : v) o << x << " ";
 return o;
}

template <typename K, typename V>
ostream& operator<<(ostream& o, const unordered_map<K, V>& m) {
  o << "{";
  for (const auto& [k, v] : m)
    o << " " << k << ": " << v << ",";
  o << "}";
  return o;
}

template <typename T>
ostream& operator<< (ostream& o, const vector<vector<T>>& v) {
 for (const auto& x : v) o << x << endl;
 return o;
}

ostream& operator<< (ostream& o, const vector<string>& v) {
 for (const auto& x : v) o << x << endl;
 return o;
}



template <typename T>
istream& operator>> (istream& i, vector<T>& v) {
  for (auto& x : v) i >> x;
  return i;
}

istream& operator>> (istream& i, pair<int, int>& p) {
  i >> p.first >> p.second;
  return i;
}



int main() {
  ios::sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  vector<int> in(n + 1), out(n + 1);
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    ++out[u];
    ++in[v];
  }
  long long hi = 0, lo = 0;
  for (int i = 1; i <= n; ++i) {
    if (in[i] > out[i]) hi += in[i] - out[i];
    if (out[i] > in[i]) lo += out[i] - in[i];
  }
  cout << max(0ll, max(hi, lo) - 1) << endl;

  return 0;
}