#include<bits/stdc++.h>

using namespace std;
const int maxm = 2e5+8;
int ct[maxm],tp[maxm],sz[maxm];
vector<int>edge[maxm];
int ans = 0;
void dfs(int now,int fa){
    if(edge[now].size() == 1){
        tp[now] = 1;
        sz[now] = 1;
    }
    int flag = 0;
    for(auto u:edge[now]){
        if(u == fa) continue;
        dfs(u,now);
        sz[now] += sz[u];
        if(tp[u]) flag = 1;
    }
    if(flag) ans += sz[now] - 1;
}
void solve(){
    int n;cin>>n;
    for(int i=1;i<=n;i++) ct[i] = 0,tp[i] = 0,ans = 0,sz[i] = 0,edge[i].clear();
    for(int i=1;i<n;i++){
        int u,v;cin>>u>>v;
        ct[u]++,ct[v]++;
        edge[u].push_back(v);
        edge[v].push_back(u);
    }
    int num = 0;
    for(int i=1;i<=n;i++){
        if(ct[i] == 1) ++num;
    }
    if(num == n-1 or (num == 2 and n == 2)){
        cout<<"-1\n";
        return;
    }
    cout<<(num+1)/2<<'\n';
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int T;cin>>T;
    while(T--) solve();
    return 0;
}