#include <bits/stdc++.h>
using namespace std;

int main() {
  int N, M, Odd = 0; cin >> N >> M;
  vector<bool> seen(2 * N + 1);
  vector<vector<int>> Graph(2 * N + 1);

  for (int i = 0; i < M; i++) {
    int A, B; cin >> A >> B;
    Graph.at(A).push_back(B);
    Graph.at(B).push_back(A);
  }

  for (int i = 1; i <= 2 * N; i++) {
    if (seen.at(i)) continue;
    int Count = 0;

    auto DFS = [&](auto DFS, int x) {
      if(seen.at(x)) return;
      seen.at(x) = true;
      Count++;
      for (int to : Graph.at(x)) DFS(DFS, to);
    };

    DFS(DFS, i);
    if (Count % 2) Odd++;
  }

  cout << Odd / 2 << endl;
}