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

typedef long long ll;
//typedef modint1000000007 mint;
const int MOD = 1000000007;
#define all(x) x.begin(), x.end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
const int inf = 1 << 30;
const ll INF = 1LL << 60;
const int dx[8] = {1, 0, -1, 0, -1, -1, 1, 1};
const int dy[8] = {0, 1, 0, -1, -1, 1, -1, 1};
template <class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; }
template <class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; }

struct unionfind{
    vector<int> par;

    unionfind(int n) : par(n) {
        rep(i, n) par[i] = -1;
    }

    int root(int x){
        if(par[x] < 0) return x;
        return par[x] = root(par[x]);
    }

    bool same(int x, int y){
        return root(x) == root(y);
    }

    void connect(int x, int y){
        int rx = root(x), ry = root(y);
        if(rx == ry) return;
        if(par[rx] < par[ry]) swap(rx, ry);
        par[ry] += par[rx];
        par[rx] = ry;
    }
};

int main(){
    int n, m;
    cin >> n >> m;

    unionfind uf(2 * n);
    rep(i, m){
        int a, b;
        cin >> a >> b;
        uf.connect(a - 1, b - 1);
    }

    int ans = 0;
    rep(i, 2 * n){
        if(uf.par[i] < 0) ans -= uf.par[i] % 2;
    }

    cout << ans / 2 << endl;

    return 0;
}