#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
#define rep(i,n) for(ll i=0;i<(n);++i)
#define reps(i,n) for(ll i=1;i<=(n);++i)
#define repr(i,n) for(ll i=2;i*i<=(n);++i)
#define ll long long
#define all(x) (x).begin(),(x).end()
#define sz(x) ((string)(x).size())
#define pb push_back
#define pob pop_back()
#define MMod (ll)1000000007
#define mmod (ll)998244353
#define setp(x) setprecision((ll)(x))
#define INF (ll)(1000000000000000000)
#define mp make_pair
using namespace std;
using pii=pair<int, int>;
using pll=pair<ll,ll>;
using vi=vector<int>;
using vc=vector<char>;
using vb=vector<bool>;
using vl=vector<long long>;
using vvi=vector<vi>;
using vvl=vector<vl>;
using vvc=vector<vc>;
using vvb=vector<vb>;
using vpi=vector<pii>;
using vpl=vector<pair<ll,ll>>;
using vs=vector<string>;
using pqi=priority_queue<int>;
vpi fs={mp(1,0),mp(-1,0),mp(0,1),mp(0,-1)};
const ll inf=1e18;

int main(){
  int n,m; cin>>n>>m;
  vvi p(2*n+1);
  rep(i,m){
    int a,b; cin>>a>>b;
    p[a].pb(b);
    p[b].pb(a);
  }
  vi d(2*n+1,-1);
  int k=0;
  queue<int> bfs;
  map<int,int> aa;
  reps(i,2*n){
    if(d[i]!=-1) continue;
    bfs.push(i);
    d[i]=k;
    aa[k]++;
    while(!bfs.empty()){
      int a=bfs.front();
      bfs.pop();
      rep(i,p[a].size()){
        if(d[p[a][i]]==-1){
          bfs.push(p[a][i]);
          d[p[a][i]]=k;
          aa[k]++;
        }
      }
    }
    k++;
  }
  int count=0;
  rep(i,k) count+=aa[i]%2;
  cout<<count/2<<endl;
  return 0;
}