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

#define rep(i, a, b) for (int i = (int)(a); (i) < (int)(b); (i)++)
#define rrep(i, a, b) for (int i = (int)(b) - 1; (i) >= (int)(a); (i)--)
#define all(v) v.begin(), v.end()

typedef long long ll;
template <class T> using V = vector<T>;
template <class T> using VV = vector<V<T>>;

V<int> G[200010];
V<bool> used(200010);
int nc = 0;

void f(int k) {
    used[k] = 1;
    nc++;
    rep(i,0,G[k].size()) {
        int to = G[k][i];
        if (used[to]) continue;
        f(to);
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    constexpr char endl = '\n';

    int n,m;
    cin >> n >> m;
    rep(i,0,m) {
        int a,b;
        cin >> a >> b;
        G[a].push_back(b);
        G[b].push_back(a);
    }

    int cnt = 0;
    rep(i,1,2*n+1) {
        if (!used[i]) {
            nc = 0;
            f(i);
            cnt += nc % 2;
        }
    }
    cout << cnt / 2 << endl;

    return 0;
}