#include <bits/stdc++.h>

#define x first
#define y second
#define el '\n'
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int N = 3e5 + 10, INF = 0x3f3f3f3f, mod = 998244353;

inline int read() {
    int f = 1, k = 0;
    char c = getchar();
    while (c < '0' || c > '9') {
        if (c == '-') f = -1;
        c = getchar();
    }
    while (c >= '0' && c <= '9') {
        k = k * 10 + c - '0';
        c = getchar();
    }
    return f * k;
}

vector<int> G[N];

void solve() {
    int n = read();
    vector<int> deg(n + 1);
    set<int> leaf;
    for (int i = 1; i <= n; ++i) G[i].clear();
    for (int i = 1; i < n; ++i) {
        int a = read(), b = read();
        ++deg[a], ++deg[b];
    }
    for (int i = 1; i <= n; ++i) 
        if (deg[i] == n - 1) return (void)puts("-1");
        else if (deg[i] == 1) leaf.insert(i);
    int sz = leaf.size(), mxsn = 0;
    for (int i = 1; i <= n; ++i) {
        int cnt = 0;
        for (int j: G[i]) if (leaf.count(j)) ++cnt;
        mxsn = max(mxsn, cnt);
    }
    if (sz - mxsn >= mxsn) 
        cout << (sz + 1) / 2 << el;
    else 
        cout << mxsn << el;
}

int main() {
    int tcase;
    cin >> tcase;
    while (tcase--) solve();
}