#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]];
    }
    int mx=0,sum=0,g=0;
    for (int i = 1; i <= n; ++i)
    {
        if (cnt[i])
        {
            ++g;
            mx=max(mx,cnt[i]);
            sum+=cnt[i];
            //printf("[%d]\n",i);
        }
    }
    if (g == 1) {
        puts("-1");
        return;
    }
    if(mx>=(sum-mx)) {
        printf("%d\n", mx);
    }
    else printf("%d\n",(sum+1)/2);
}
int main() {
    int TT;
    scanf("%d", &TT);
    while (TT--) sol();
    return 0;
}
/*
4
2
1 2
4
1 2
2 3
3 4
4
1 2
2 3
2 4
5
1 2
3 5
2 3
3 4
*/