/**
 * @author: XiaFan
 * @date: 2023-04-13 19:58
 */
#include <bits/stdc++.h>

using i64 = long long;

void solve() {
    int n;
    std::cin >> n;
    std::vector<std::vector<int>> adj(n);
    for (int i = 0; i < n - 1; i++) {
        int u, v;
        std::cin >> u >> v;
        u--, v--;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    if (n <= 3) {
        std::cout << -1 << "\n";
        return;
    }

    int ans = 1;

    for (int i = 0; i < n; i++) {
        if (adj[i].size() > 1) continue;
        int min = n, max = 0;
        for (auto v : adj[i]) {
            for (auto u : adj[v]) {
                if (u == i) continue;
                min = std::min(min, (int)adj[u].size());
                max = std::max(max, (int)adj[u].size());
            }
        }
        // std::cerr << i + 1 << " " << min << " " << max << "\n";
        if (max == 1) {
            std::cout << -1 << "\n";
            return;
        }
        if (min == 1) {
            ans = 2;
        }
    }

    std::cout << ans << "\n";
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int t = 1;
    std::cin >> t;
    while (t--) {
        solve();
    }

    return 0;
}