#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e5 + 10;
vector<int> eg[N];
int siz[N], deg[N];
void dfs(int u, int p) {
	if(eg[u].size() == 1) siz[p] ++;
	for(auto v : eg[u]) {
		if(v == p) continue;
		dfs(v, u);
	}
}

void solve() {
	int n;
	cin >> n; 
	for(int i = 0;  i<= n; i ++) eg[i].clear(), deg[i] = siz[i] = 0;
	for(int i = 1; i < n; i ++) {
		int x, y;
		cin >> x >> y;
		eg[x].push_back(y);
		eg[y].push_back(x);
		deg[x] ++, deg[y] ++;
	}
	if(n == 2) {
		cout << -1 << "\n";
		return;
	}
	int s;
	for(int i = 1; i <= n; i ++) {
		if(deg[i] >= 2) {
			s = i;
			break;
		}
	}
	dfs(s, 0);
	vector<int> res;
 	for(int i = 1; i <= n; i ++) {
 		if(siz[i]) res.push_back(siz[i]);
 	}
 	sort(res.begin(), res.end());
 	ll ans = 0;
 	if(res.size() == 1) {
 		cout << -1 << "\n";
 		return;
 	}
 	for(int i = 1; i < res.size(); i ++) {
 		ans += res[i - 1];
		res[i] -= res[i - 1]; 		
 	}
 	cout << ans + res[(int)res.size() - 1] << "\n";
}

int main() {
	int t;
	cin >> t;
	while(t --) solve();
}