#include<iostream>
#include<algorithm>
#include<string.h>
#include<vector>
#include<queue>
using namespace std;
// #define debug(x) cout<<"[debug]"#x<<"="<<x<<endl
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const ld eps=1e-8;
const int INF=0x3f3f3f3f,mod=998244353;
const ll INFF=0x3f3f3f3f3f3f3f3f;

#ifndef ONLINE_JUDGE
#define debug(...)
#include<debug>
#else
#define debug(...)
#endif

const int N=100005;
vector<int> edg[N];
int n;
int d[N];
int res;
int dp[N];
void solve()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        edg[i].clear();
        d[i]=0;
        dp[i]=0;
    }

    for(int i=1;i<=n-1;i++)
    {
        int x,y;
        scanf("%d%d",&x,&y);

        edg[x].push_back(y);
        edg[y].push_back(x);
        d[x]++,d[y]++;
    }
    if(*max_element(d+1,d+n+1)==1)
    {
        puts("-1");
        return ;
    }

    vector<int> ver;
    for(int u=1;u<=n;u++)
    {
        int num=0;
        for(auto v:edg[u])
        {
            if(d[v]==1) num++;
        }
        if(num) ver.push_back(num);
    }
    debug(ver);
    sort(ver.begin(),ver.end(),greater<>());
    if(ver.size()==1)
    {
        puts("-1");
        return ;
    }
    int res=0;
    int las=0;
    for(auto x:ver)
    {
        int ans=min(x,las);
        x-=ans;
        las-=ans;

        res+=ans;
        las+=x;
    }
    res+=las;
    printf("%d\n",res);
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        solve();
    }
}