#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);
   long long n, m;
  cin >> n >> m;
  vector< long long> c(n + 1);
  for ( long long i = 0; i < m; ++i) {
     long long u, v;
    cin >> u >> v;
    --c[u];
    ++c[v];
  }
  long long hi = 0;
  for ( long long i = 0; i <= n; ++i) {
    if (c[i] > 0) hi += c[i];
  }

  cout << max(0ll, hi- 1) << endl;

  return 0;
}