#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

vector<int> p[100010];
int fa[100010];
void dfs(int x,int f){
    if(p[x].size()==1)fa[f]++;
    for(auto i:p[x]){
        if(i==f)continue;
        dfs(i,x);
    }
}

void solve(){
    int n;cin>>n;
    for(int i=1;i<=n;i++)p[i].clear(),fa[i]=0;
    for(int i=0;i<n-1;i++){
        int u,v;cin>>u>>v;
        p[u].push_back(v);
        p[v].push_back(u);
    }
    int r=1;
    while(r<=n&&p[r].size()==1)r++;
    if(r>n){
        cout<<"-1\n";
        return;
    }
    dfs(r,0);
    sort(fa+1,fa+n+1);
    int l=1;
    while(fa[l]==0)l++;
    if(l==n){
        cout<<"-1\n";
        return;
    }
    int r2=n,r1=n-1;
    ll ans=0;
    while(r1>=l){
        if(fa[r2]>fa[r1]){
            fa[r2]-=fa[r1];
            ans+=fa[r1];
            r1--;
        }
        else if(fa[r1]>fa[r2]){
            fa[r1]-=fa[r2];
            ans+=fa[r2];
            r2=r1;
            r1--;
        }
        else{
            ans+=fa[r2];
            fa[r1]=fa[r2]=0;           
            r2=r1-1;
            r1=r2-1;
        }
    }
    ans+=fa[l];
    cout<<ans<<"\n";
}

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    int n;
    cin>>n;
    while(n--)solve();
    return 0;
}