#include <algorithm>
#include <iostream>
#include <vector>
#include <queue>

using namespace std;

const int N = 2e5 + 5;

vector<int> ed[N];
int n;

int solve() {
  cin >> n;
  for (int i = 1;i <= n; i++) ed[i].clear();
  for (int i = 0; i < n-1; i++) {
    int u, v;
    cin >> u >> v;
    ed[u].push_back(v);
    ed[v].push_back(u);
  }

  if (n <= 3) return -1;
  vector<int> g(n + 1);
  for (int i = 1; i <= n; i++) {
    if (ed[i].size() == 1) {
      g[ed[i][0]]++;
    }
  }

  priority_queue<int> pq;
  for (int cnt : g) if (cnt != 0) pq.push(cnt);
  if (pq.size() == 1) return -1;
  int ans = 0;
  int left = 0;
  while (!pq.empty()) {
    int t1 = pq.top(); pq.pop();
    if (pq.empty()) {
      left = t1;
      break;
    }
    int t2 = pq.top(); pq.pop();
    ans += t2;
    if (t1 > t2)
      pq.push(t1 - t2);
  } 

  ans += left;
  return ans;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  int t; cin >> t; while (t--)
    printf("%d\n", solve());
  
}