#include<iostream>
#include<vector>
using namespace std;
const int MAXN = 100005;
vector<int> V[MAXN]={};
int F[MAXN]={},d[MAXN]={},t[MAXN]={};
void DFS(int x,int fa)
{
    F[x] = fa;
    for(auto v:V[x]){
        if(v == fa){continue;}
        DFS(v,x);
    }
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    int T = 0;
    cin>>T;
    while(T--){
        int n = 0;
        cin>>n;
        for(int i=0;i<=n;++i){
            V[i].clear();
            F[i] = 0;
            d[i] = 0;
            t[i] = 0;
        }
        int u=0,v=0;
        for(int i=1;i<n;++i){
            cin>>u>>v;
            V[u].push_back(v);
            V[v].push_back(u);
            ++d[u];++d[v];
        }
        DFS(1,0);
        int S1 = 0,S2 = 0;
        for(int i=1;i<=n;++i){
            if(d[i] == 1){
                ++S1;
                ++t[F[i]];
            }
        }
        for(int i=0;i<=n;++i){
            S2 = max(t[i],S2);
        }
        if(S1 >= n - 1){
            cout<<"-1\n";
            continue;
        }
        cout<<max((S1+1)/2,S2)<<"\n";
    }
    return 0;
}