ll n,r,u[2d5],w[2d5];
vector<ll> v[2d5];
deque<ll> q;

ll f(ll j){
	ll a=1;
	w[j]=1;
	rep(i,v[j].size()){
		ll x=v[j][i];
		if(!w[x]){
			if(f(x)==1){
				a=2;
			}
		}
	}
	r+=a==1;
	return a;
}

{
	rd(n,u(n*2-2));
	rep(i,n*2-2)v[u[i]].push_back(u[i^1]);
	f(1);
	wt(r);
}