#include <bits/stdc++.h>

using namespace std;

const int N = 1e5 + 10;

vector<int> G[N];
int cnt_leaf[N], direct_leaf[N];

void init(int n);
void dfs(int u, int par);
int solve(int n);

int main()
{
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    int T, n;
    cin >> T;
    while (T--)
    {
        cin >> n;
        init(n);
        cout << solve(n) << "\n";
    }
    return 0;
}

void init(int n)
{
    for (int i = 1; i <= n; i++)
    {
        G[i].clear();
        cnt_leaf[i] = direct_leaf[i] = 0;
    }
    int u, v;
    for (int i = 1; i < n; i++)
    {
        cin >> u >> v;
        G[u].push_back(v);
        G[v].push_back(u);
    }
}

int solve(int n)
{
    int root = 0;
    for (int i = 1; i <= n; i++)
        if (G[i].size() != 1)
        {
            root = i;
            break;
        }
    if (root == 0 || G[root].size() == n - 1)
        return -1;
    dfs(root, root);
    int tmp1 = cnt_leaf[root], tmp2 = 0;
    for (int i = 1; i <= n; i++)
    {
        // cout << i << " " << cnt_leaf[i] << " " << direct_leaf[i] << endl;
        tmp2 = max(tmp2, direct_leaf[i]);
    }
    // cout << tmp1 << " " << tmp2 << endl;
    tmp1 -= tmp2;
    if (tmp1 <= tmp2)
        return tmp2;
    return (tmp1 + tmp2) / 2;
}

void dfs(int u, int par)
{
    if (G[u].size() == 1)
    {
        cnt_leaf[u] = 1;
        return;
    }
    for (auto v : G[u])
        if (v != par)
        {
            dfs(v, u);
            cnt_leaf[u] += cnt_leaf[v];
            if (G[v].size() == 1)
                direct_leaf[u]++;
        }
}