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

		auto dfs = [&](auto & self, int u, int fa) -> void{
			p[u] = fa;
			for (auto ne : adj[u]) {
				if (ne != fa) {
					self(self, ne, u);
				}
			}
		};

		dfs(dfs, 1, 0);

		for (int i = 1; i <= n; ++ i) {
			if (d[i] == 1) sz[p[i]] += 1;
		}

		int sum = 0, mx = 0;
		for (int i = 0; i <= n; ++ i) {
			mx = max(mx, sz[i]);
			sum += sz[i];
		}

		cout << max((sum + 1) / 2, mx) << '\n';
	}

	return 0;
}