#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using P = pair<ll,ll>;
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define rep2(i,m,n) for(int (i)=(m);(i)<(n);(i)++)
#define rep2ll(i,m,n) for(ll (i)=(m);(i)<(n);(i)++)
#define ALL(obj) (obj).begin(), (obj).end()
#define rALL(obj) (obj).rbegin(), (obj).rend()
const ll INF60 = 1LL<<60;//1152921504606846976
const int INF30 = 1<<30;
using mint = modint998244353;
using VL = vector<ll>;
using VVL = vector<VL>;
using VVVL = vector<VVL>;
using VM = vector<mint>;
using VVM = vector<VM>;
using VVVM = vector<VVM>;
using VD = vector<double>;
using VVD = vector<VD>;
using VVVD = vector<VVD>;
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; }



int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n, m; cin>>n>>m;
    VL u(m), v(m); 
    rep(i,m) cin>>u[i]>>v[i], u[i]--, v[i]--;
    VL din(n, 0), dout(n, 0);
    atcoder::dsu uf(n);
    rep(i,m){
        uf.merge(u[i], v[i]);
        din[v[i]]++;
        dout[u[i]]++;
    }
    ll ans = 0;
    ll sz = 0;
    for(auto g:uf.groups()){
        ll dsum = 0;
        for(auto x:g) dsum += abs(din[x] - dout[x]);
        ans += max(0LL, dsum/2-1);
        sz += max(din[g[0]],dout[g[0]])!=0;
    }
    cout<<ans+max(0LL,sz-1);
    
    return 0;
}