#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2e5 + 10;
int n;
vector<int> p[N];
priority_queue<int, vector<int>> pr, nu;

void dfs(int x, int fa)
{
    int num = 0;    
    for (int t : p[x])
    {
        if (p[t].size() == 1) ++num;
        else if (t != fa) dfs(t, x);
    }
    if (num) pr.push(num);
}

void solve()
{
    cin >> n;
    pr = nu;
    for (int i = 1; i <= n; ++i) p[i].clear();
    for (int i = 1; i < n; ++i)
    {
        int u, v;
        cin >> u >> v;
        p[u].push_back(v);
        p[v].push_back(u);
    }
    int res = 0;
    dfs(1, 0);
    // cout << pr.size() << ' ';
    if (pr.size() == 1 || pr.top() == n - 1) return cout << "-1\n", void();
    while (pr.size() > 1)
    {
        int x = pr.top(); pr.pop();
        int y = pr.top(); pr.pop();
        // cout << "\n**" << x << ' ' << y << "**\n";
        res += y;
        if (x - y > 0) pr.push(x - y);
    }
    if (pr.size()) res += pr.top();
    cout << res << '\n';
}

int main(void)
{
    ios::sync_with_stdio(false); std::cin.tie(nullptr); std::cout.tie(nullptr);
    int t = 1;
    cin >> t;
    while (t--) solve();
    return 0;
}