#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<(int)n; i++)
#define repi(i,m,n) for(int i=(int)m; i<=(int)n; i++)
#define rrep(i,n) for(int i=(int)n-1; i>=0; i--)
#define rrepi(i,m,n) for(int i=(int)n; i>=(int)m; i--)
#define all(x) x.begin(),x.end()
template <typename T> inline bool chmin(T& a, const T& b) { return a > b ? a = b, true : false; };
template <typename T> inline bool chmax(T& a, const T& b) { return a < b ? a = b, true : false; };
template <typename T> void uniq(std::vector<T> &v){
    std::sort(v.begin(),v.end());
    v.erase(unique(v.begin(),v.end()),v.end());
}
using ll = long long;

int main(){
    int n,m; cin >> n >> m;
    vector<vector<int>> g(2*n);
    rep(i,m){
        int a,b; cin >> a >> b;
        a--; b--;
        g[a].emplace_back(b);
        g[b].emplace_back(a);
    }

    vector<bool> p(2*n,false);
    vector<int> sz;
    rep(i,2*n){
        if(p[i]) continue;
        int cnt = 1;
        p[i] = true;
        queue<int> q;
        q.emplace(i);
        while(!q.empty()){
            int j = q.front(); q.pop();
            for(auto e : g[j]) if(!p[e]){
                p[e] = true;
                cnt++;
                q.emplace(e);
            }
        }
        sz.emplace_back(cnt);
    }

    cout << count_if(all(sz),[](int a){return a%2 != 0;})/2 << endl;
    
    return 0;
}