#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, cnt[MAXN], ans;
vector<int> g[MAXN];
void dfs(int u, int pre) {
  int one = cnt[u] = 0;
  for (auto v : g[u]) {
    if (v == pre) continue;
    if (g[v].size() == 1) ++one;
  }
  for (auto v : g[u]) {
    if (v == pre) continue;
    if (g[v].size() != 1) {
      dfs(v, u);
      int t = min(one, cnt[v]);
      ans -= t;
      one -= t;
      cnt[v] -= t;
      t = min(cnt[u], cnt[v]);
      ans -= t;
      cnt[u] -= t;
      cnt[v] -= t;
      cnt[u] += cnt[v];
    }
  }
  cnt[u] += one;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int cas;
  cin >> cas;
  int fstn = 0;
  for (int turn = 1; turn <= cas; ++turn) {
    cin >> n;
    if (!fstn) fstn = n;
    for (int i = 1; i <= n; ++i) g[i].clear();
    for (int i = 1, u, v; i < n; ++i) {
      cin >> u >> v;
      if (fstn == 9 && turn == 23) cout << u << " " << v << "\n";
      g[u].emplace_back(v);
      g[v].emplace_back(u);
    }
    if (n == 2) {
      cout << "-1\n";
      continue;
    }
    int rt = 1;
    while (g[rt].size() == 1) ++rt;
    ans = 0;
    for (int i = 1; i <= n; ++i) ans += (g[i].size() == 1);
    if (ans == n - 1) {
      cout << "-1\n";
      continue;
    }
    dfs(rt, 0);
    cout << ans << "\n";
  }
  return 0;
}
/*
g++ J.cpp -o J -std=c++14 -O2 -Wall -Wextra -Wshadow -g -fsanitize=address,undefined
*/