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

void QAQ() {
    int n;
    cin >> n;

    vector adj(n + 1, vector<int>());

    for (int i = 1; i < n; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].emplace_back(v), adj[v].emplace_back(u);
    }

    map<int, int> cnt;
    auto dfs = [&](auto &&self, int x, int fa) -> void {
        if (adj[x].size() == 1) {
            cnt[fa]++;
            return;
        }
        for (auto &y : adj[x]) {
            if (y == fa) continue;
            self(self, y, x);
        }
    };

    int root = 0;
    for (int i = 1; i <= n; i++) {
        if (adj[i].size() > 1) {
            root = i;
            break;
        }
    }
    if (!root) {
        cout << "-1\n";
        return;
    }

    dfs(dfs, root, 0);
    if (cnt.size() == 1) {
        cout << "-1\n";
    } else {
        int mx = 0, tot = 0;
        vector<int> tmp;
        for (auto [a, b] : cnt) {
            tmp.push_back(b);
        }
        sort(tmp.begin(), tmp.end());
        int ans = 0;
        for (int i = 1; i < tmp.size(); i++) {
            ans += tmp[i - 1];
            tmp[i] -= tmp[i - 1];
        }
        ans += tmp.back();
        cout << ans << "\n";
    }
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int t = 1;
    cin >> t;

    while (t--) {
        QAQ();
    }
    return 0;
}