#include <cstdio>
#include <cstring>
#include <cctype>
#include <algorithm>
#include <iostream>
#include <queue>
typedef long long LL;
using namespace std;
inline int read() {
    int num = 0 ,f = 1; char c = getchar();
    while (!isdigit(c)) f = c == '-' ? -1 : f ,c = getchar();
    while (isdigit(c)) num = (num << 1) + (num << 3) + (c ^ 48) ,c = getchar();
    return num * f;
}
const int N = 1e5 + 5;
int d[N] ,n;
signed main() {
    int t = read();
    while (t--) {
        n = read();
        for (int i = 1; i <= n - 1; i++) {
            int u = read() ,v = read();
            d[u]++ ,d[v]++;
        }
        int maxn = 0 ,cnt = 0;
        for (int i = 1; i <= n; i++) {
            maxn = max(maxn ,d[i]);
            cnt += d[i] == 1;
        }
        if (maxn == n - 1) puts("-1");
        else printf("%d\n" ,(cnt + 1) / 2);
        for (int i = 1; i <= n; i++) d[i] = 0;
    }
    return 0;
}