#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using i128 = __int128;
using u128 = unsigned __int128;
template <typename T>
void chkmax(T &x, const T &y) {
  if (x < y) x = y;
}
template <typename T>
void chkmin(T &x, const T &y) {
  if (y < x) x = y;
}
constexpr int MAXN = 1e5 + 10;
int n, ans;
vector<int> g[MAXN];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int cas;
  cin >> cas;
  for (int turn = 1; turn <= cas; ++turn) {
    cin >> n;
    for (int i = 1; i <= n; ++i) g[i].clear();
    for (int i = 1, u, v; i < n; ++i) {
      cin >> u >> v;
      g[u].emplace_back(v);
      g[v].emplace_back(u);
    }
    if (n == 2) {
      cout << "-1\n";
      continue;
    }
    ans = 0;
    for (int i = 1; i <= n; ++i) ans += (g[i].size() == 1);
    vector<int> vec;
    for (int i = 1; i <= n; ++i) {
      if (g[i].size() != 1) {
        int cnt = 0;
        for (auto j : g[i]) cnt += (g[j].size() == 1);
        vec.emplace_back(cnt);
      }
    }
    int sum = accumulate(vec.begin(), vec.end(), 0), mx = *max_element(vec.begin(), vec.end());
    ans -= min(sum / 2, sum - mx);
    cout << ans << "\n";
  }
  return 0;
}
/*
g++ J.cpp -o J -std=c++14 -O2 -Wall -Wextra -Wshadow -g -fsanitize=address,undefined
*/