#include <bits/stdc++.h>
using namespace std;
#define int long long
#define x first
#define y second
#define PII pair<int,int>
const int mod=998244353;
const int N=1e5+100;
vector<int>g[N];
int d[N];
multiset<int>st;
void dfs(int u,int fa)
{
	if(d[u]==1)	return;
	int t=0;
	for(int j : g[u])
	{
		if(j==fa)	continue;
		if(d[j]==1)	t++;
		dfs(j,u);
	}
	st.insert(t);
}
void solve(){
	int n;
	scanf("%lld",&n);
	for(int i=1;i<=n;i++)	g[i].clear(),d[i]=0;
	st.clear();
	for(int i=1;i<n;i++)
	{
		int u,v;
		scanf("%lld%lld",&u,&v);
		g[u].push_back(v),g[v].push_back(u);
		d[u]++,d[v]++;
	}
	int res=0,ans=0;
	for(int i=1;i<=n;i++)
		if(d[i]==1)	res++;
	if(res>=n-1)
	{
		puts("-1");
		return;
	}
	for(int i=1;i<=n;i++)
		if(d[i]>1)
		{
			dfs(i,-1);
			break;
		}
	while(st.size()>1)
	{
		auto it = st.rbegin();
		int x = *it;
		it--;
		int y = *it;
		st.erase(st.find(*it));
		it++;
		st.erase(st.find(*it));
		ans+=y;
		//cout<<x<<" "<<y<<"----------"<<endl;
		x-=y;
		if(x)	st.insert(x);
	}
	if(st.size())	ans+=*st.begin();
	printf("%lld\n",ans);
}
signed main() {
	int T=1;
//	freopen("C:\\Users\\86153\\Desktop\\data.in.txt","r",stdin); //´ÓÎļþÖлñÈ¡ÊäÈëÁ÷
//	freopen("C:\\Users\\86153\\Desktop\\data1.out.txt","w",stdout); //°ÑÊä³öתµ½ÎļþÖÐ
	//init();
	cin>>T;
	while(T--) {
		solve();
	}
	//return 0;
}