#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
int n, cnt[maxn], a, b;
vector<int>v[maxn];
priority_queue<int>q;
void sol() {
    scanf("%d", &n);
    while (!q.empty()) q.pop();
    for (int i = 1; i <= n; ++i) v[i].clear(), cnt[i] = 0;
    for (int i = 1; i < n; ++i) {
        scanf("%d%d", &a, &b);
        v[a].push_back(b);
        v[b].push_back(a);
    }
    if (n == 2) {
        puts("-1");
        return;
    }
    for (int i = 1; i <= n; ++i) {
        if (v[i].size() == 1) ++cnt[v[i][0]];
    }
    for (int i = 1; i <= n; ++i) if (cnt[i]) q.push(cnt[i]);
    if (q.size() == 1) {
        puts("-1");
        return;
    }
    int ans = 0;
    while (q.size() > 1) {
        a = q.top();
        q.pop();
        b = q.top();
        q.pop();
        ans += b;
        if (a != b) q.push(a - b);
    }
    if (q.size()) ans += q.top();
    printf("%d\n", ans);
}
int main() {
    int TT;
    scanf("%d", &TT);
    while (TT--) sol();
    return 0;
}