#include <bits/stdc++.h>
#define int long long
using namespace std;

string to_string(string s) { return s; }
template <typename T> string to_string(T v) {
  bool first = true;
  string res = "[";
  for (const auto &x : v) {
    if (!first)
      res += ", ";
    first = false;
    res += to_string(x);
  }
  res += "]";
  return res;
}

void dbg_out() { cout << endl; }
template <typename Head, typename... Tail> void dbg_out(Head H, Tail... T) {
  cout << ' ' << to_string(H);
  dbg_out(T...);
}

#ifdef DEBUG
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif

void solve() {
  int nbSommets;
  cin >> nbSommets;

  vector<int> deg(nbSommets);
  for (int i = 1; i < nbSommets; ++i) {
    int u, v;
    cin >> u >> v;
    --u, --v;
    deg[u]++;
    deg[v]++;
  }

  int feuilles = 0;
  for (int u = 0; u < nbSommets; ++u) {
    feuilles += deg[u] == 1;
    if (deg[u] + 1 == nbSommets) {
      cout << -1 << '\n';
      return;
    }
  }
  cout << (feuilles + 1) / 2 << '\n';
}

signed main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(0);

  int nbTests;
  cin >> nbTests;
  for (int iTest(0); iTest < nbTests; ++iTest)
    solve();
}