#include<iostream>
#include<cstring>
#include<vector>
using namespace std;
using LL = long long;

int main(){

#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif

    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);

    int T;
    cin >> T;
    while(T--){
        int n;
        cin >> n;
        vector<int> d(n + 1);
        for(int i = 0; i < n - 1; i++){
            int a, b;
            cin >> a >> b;
            d[a] += 1, d[b] += 1;
        }
        int leafs = 0;
        for(int i = 1; i <= n; i++) leafs += (d[i] == 1);
        if (leafs >= n - 1){
            cout << -1 << '\n';
            continue;
        }
        cout << (leafs + 1) / 2 << '\n';
    }

}