#include<bits/stdc++.h>
using namespace std;

int main() {

	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);

	int _;
	cin >> _;
	while (_ --) {
		int n;
		cin >> n;

		vector<int> p(n + 1), d(n + 1, 0), sz(n + 1, 0);
		vector<pair<int, int>> edges;
		for (int i = 1; i < n; ++ i) {
			int u, v;
			cin >> u >> v;
			d[u] += 1, d[v] += 1;
			edges.push_back({u, v});
		}

		int fd = 0;
		for (int i = 1; i <= n; ++ i) {
			fd += (d[i] == 1);
		}

		if (fd == n - 1 or (fd == 2 and n == 2)) {
			cout << "-1\n";
			continue;
		}
		
		for(int i = 0; i < n - 1; ++ i){
			int u = edges[i].first, v = edges[i].second;
			if(d[u] == 1) sz[v] += 1;
			if(d[v] == 1) sz[u] += 1;
		}

		int ans = (fd + 1) / 2;

		for (int i = 1; i <= n; ++ i) {
			ans = max(ans, sz[i]);
		}

		cout << ans << '\n';
	}

	return 0;
}