#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>
#include <set>
using std::cin, std::cout;

#define F(i, a, b) for(int i = a; i <= (b); ++i)
#define F2(i, a, b) for(int i = a; i < (b); ++i)
#define dF(i, a, b) for(int i = a; i >= (b); --i)
#define debug(...) std::fprintf(stderr, __VA_ARGS__)
#define Debug debug("Passing [%s] in LINE %d\n", __FUNCTION__, __LINE__)

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

const int MN = 100005;

int n, d[MN];

void Solve() {
    cin >> n;
    F(i, 1, n) d[i] = 0;
    F(i, 1, n - 1) {
        int x, y;
        cin >> x >> y;
        ++d[x];
        ++d[y];
    }
    if (n <= 3)
        return void(cout << -1 << '\n');
    int c = 0;
    F(i, 1, n)
        if (d[i] == 1)
            ++c;
    if (c == n - 1)
        return void(cout << -1 << '\n');
    cout << (c + 1) / 2 << '\n';
}