#include <fstream>
#include <vector>

using namespace std;

const int N = 8200;

vector<int> gr[2 * N];
pair<int, int> dp[2 * N];
bool viz[2 * N];

void dfs(int nod) {
  viz[nod] = true;
  dp[nod].second = 1;
  for (auto nxt: gr[nod]) {
    if (viz[nxt]) continue;
    dfs(nxt);
    dp[nod].first += max(dp[nxt].first, dp[nxt].second);
    dp[nod].second += dp[nxt].first;
  }
}

int main() {
  ifstream cin("felinare.in");
  ofstream cout("felinare.out");
  int n, m;
  cin >> n >> m;
  while (m--) {
    int x, y;
    cin >> x >> y;
    x = 2 * x;
    y = 2 * y + 1;
    gr[x].push_back(y);
    gr[y].push_back(x);
  }
  cin.close();
  int ans = 0;
  for (int i = 2; i <= 2 * n + 1; ++i)
    if (!viz[i]) {
      dfs(i);
      ans += max(dp[i].first, dp[i].second);
    }
  cout << ans << "\n";
  cout.close();
  return 0;
}