#include<bits/stdc++.h>

using namespace std;
const int maxm = 2e5+8;
int ct[maxm],sz[maxm];
vector<int>edge[maxm];
priority_queue<int>Q;
void dfs(int now,int fa){
    for(auto u:edge[now]){
        if(u == fa) continue;
        dfs(u,now);
        if(ct[u] == 1) ++sz[now];
    }
    if(fa != -1 and ct[fa] == 1) ++sz[now];
    if(sz[now]) Q.push(sz[now]);
}
void solve(){
    int n;cin>>n;
    for(int i=1;i<=n;i++) ct[i] = 0,edge[i].clear(),sz[i] = 0;
    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);
    }
    //so?
    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;
    }
    dfs(1,-1);
    int ans = 0;
    while(Q.size() > 1){
        int A = Q.top();Q.pop();
        int B = Q.top();Q.pop();
        ans += B;
        if(A > B) Q.push(A - B);
    }
    if(Q.size()) ans += Q.top(),Q.pop();
    cout<<ans<<'\n';
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int T;cin>>T;
    while(T--) solve();
    return 0;
}