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

using ll = long long;
using i64 = long long;

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

    if (n == 2) {
        cout << -1 << '\n';
        return;
    }
    
    vector<int> cnt(n + 1);
    for (int i = 1; i <= n; i++) if (g[i].size() == 1) {
        cnt[g[i][0]]++;
    }

    if (count(cnt.begin() + 1, cnt.end(), 0) == n - 1) {
        cout << -1 << '\n';
        return;
    }

    int sum = 0;
    int ans = 0;
    for (int i = 1; i <= n; ++i) {
        if (cnt[i] > 0) {
            int minn = min(sum, cnt[i]);
            sum -= minn;
            cnt[i] -= minn;
            ans += minn;
            sum += cnt[i];
        }
    }

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

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

    int t = 1;
    cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}