#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < n; i++)
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)

ll seen[200005] ;

int main(){
    ll n , m ;
    cin >> n >> m ;
    dsu f(2*n) ;
    rep(i,m){
        ll a , b ;
        cin >> a >> b ;
        a--, b-- ;
        f.merge(a,b) ;
    }
    ll ans = 0 ;
    // 知らないどおしのかず
    rep(i,2*n){
        if( seen[f.leader(i)] ) continue;
        seen[f.leader(i)] = 1 ;
        if( f.size(i) % 2 == 1 ) ans += 1 ;
    }
    cout << ans / 2 << endl ;
}