#include <bits/stdc++.h>
using namespace std;
const int N = 2e5+10;
vector<int> g[N];
int rt=0;
int mxd=0;
int dep[N];
int ans = 0;
void dfs(int x,int f,int dp){
    if(dp > mxd) rt = x, mxd = dp;
    for(int y:g[x]){
        if(y==f) continue;
        dfs(y,x,dp+1);
    }
}
int d = 0;
void dfs2(int x,int f){
    int cnt=0;
    dep[x]=dep[f]+1;
    d = max(dep[x],d);
    for(auto y:g[x]){
        if(y==f) continue;
        dfs2(y,x);
        cnt++;
    }
    if(!cnt) ans++;
}
void solve(){
    int n;
    cin>>n;
    rt = 0;
    mxd = 0;
    ans = 0;
    d = 0;
    for(int i=1;i<=n;i++){
        g[i].clear();
        dep[i]=0;
    }
    for(int i=1;i<n;i++){
        int x,y;
        cin>>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    dfs(1,0,1);
    dep[rt] = 1;
    dfs2(rt,0);
    if(d <= 3){
        cout<<"-1"<<endl;
    }
    else{
        cout<<ans<<endl;
    }
}
int main()
{
	ios::sync_with_stdio(false);
	int T;
    cin>>T;
    while(T--) solve();
    return 0;
}