#include<bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;

vector <int> v[N];
int d[N];

int main()
{
	int T;
	cin >> T;
	while (T > 0)
	{
		memset(d, 0, sizeof(d));
		T--;
		int n;
		scanf("%d", &n);
		for (int i = 1; i <= n; i++)
		{
			v[i].clear();
		}
		for (int i = 1; i < n; i++)
		{
			int x, y;
			scanf("%d %d", &x, &y);
			v[x].push_back(y);
			v[y].push_back(x);
			d[x] ++;
			d[y] ++;
		}
		if (n == 2 || n == 3)
		{
			cout << -1 << endl;
			continue;
		}
		int f = 1, t = 0;
		for (int i = 1; i <= n; i++)
		{
			if (d[i] == n - 1) 
			{
				f = -1;
				break;
			}
			if (d[i] == 1) t++;
		}
		if (f == -1) cout << -1 << endl;
		else cout << t - 1 << endl;
	}
	return 0;
}