#include <bits/stdc++.h>
#define endl "\n"
using namespace std;
typedef long long LL;
typedef pair<int, int> PII;
const int N = 2e5 + 10, INF = 0x3f3f3f3f, mod = 1e9 + 7;
int du[N], cnt[N];
vector<int> v[N];

void solve()
{
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)
        du[i] = cnt[i] = 0, v[i].clear();
        
    for (int i = 1; i < n; i++)
    {
        int a, b;
        cin >> a >> b;
        du[a]++, du[b]++;
        v[a].push_back(b);
        v[b].push_back(a);
    }

    priority_queue<int> q;
    for (int i = 1; i <= n; i++)
    {
        for (int x: v[i])
            if (du[x] == 1) cnt[i]++;
        if (cnt[i]) q.push(cnt[i]);
        if (v[i].size() + 1 == n)
        {
            cout << "-1\n";
            return;
        }
    }
    
    if (q.size() == 1)
    {
        cout << "-1\n";
        return;
    }
    
    int ans = 0;
    while (q.size() > 1)
    {
        int a = q.top();q.pop();
        int b = q.top();q.pop();
        if (a != b) q.push(a - b);
        ans += b;
    }

    if (q.size())   ans += q.top();

    cout << ans;
    cout << endl;
}

signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);

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