graph g;
priority_queue<ll> f(ll i,ll p){
	priority_queue<ll> q;
	rep[g.edge[i]](j,g.es[i]){
		if(j!=p){
			auto r=f(j,i);
			if(r.size()>q.size()){
				swap(r,q);
			}
			while(!r.empty()){
				ll x=r.top();
				r.pop();
				q.push(x);
			}
		}
	}
	if(q.size()==0){
		q.push(1);
	}
	else
	if(q.size()==1){
		ll x=q.top();
		q.pop();
		q.push(x+1);
	}
	else{
		ll x=q.top();
		q.pop();
		ll y=q.top();
		q.pop();
		q.push(x+y+1);
	}
	return q;
}
{
	ll@n;
	int a[n],b[];
	rd((a,b)(n-1));
	g.setEdge(n+1,n-1,a,b);
	auto r=f(1,1);
	wt(r.top());
}