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