// #include<iostream>
// #include<cstdio>
// #include<algorithm>
// #include<cstring>
// #include<cmath>
// #include<vector>
// #include<queue>
// #include<map>
// #include<unordered_map>
// #include<bitset>
// #include<set>
// #include<stack>
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define pii pair<int,int>
#define pll pair<ll,ll>
#define inf 0x3f3f3f3f
#define endl "\n"
#define pi acos(-1)
#define eps 1e-9
const ll mod=1e9+7;
ll qpow(ll base,ll power){
    ll res=1;
    while(power>0){
        if(power&1) res=base*res%mod;
        power>>=1;
        base=base*base%mod;
    }
    return res;
}

ll gcd(ll a,ll b){
    return b==0?a:gcd(b,a%b);
}

ll lcm(ll a,ll b){
    return a/gcd(a,b)*b;
}
double dis(double x,double y,double x1,double y1){
    return sqrt((x-x1)*(x-x1)+(y-y1)*(y-y1));
}
ll dis1(ll x,ll y,ll z,ll x1,ll y1,ll z1){
    return (x-x1)*(x-x1)+(y-y1)*(y-y1)+(z-z1)*(z-z1);
}
double chaji(double x1,double x2,double y1,double y2){
    return x1*y2-x2*y1;
}
const int N=1e6+10;
int in[N];
void solve() {
    int n;
    cin >> n;
    for(int i=1;i<=n;i++) in[i]=0;
    int x,y;
    for(int i=1;i<n;i++){
        cin >> x >> y;
        in[x]++;
        in[y]++;
    }
    if(n==2){
        cout << -1 << endl;
        return;
    }
    int cnt=0;
    for(int i=1;i<=n;i++){
        if(in[i]==1) cnt++;
    }
    if(cnt==n-1){
        cout << -1 << endl;
        return;
    }
    cout << cnt-1 << endl;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int t=1;
    cin >> t;
    //scanf("%d",&t);
    while(t--){
        //cout << "Case #" << ++cnt << ": ";
        solve();
    }
}