#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

int read() {
	int r=0,w=1;char ch=getchar();
	while(ch < '0' || ch > '9'){if (ch=='-') {w=-1;}ch=getchar();}
	while(ch >= '0' && ch <='9') {r = r*10+(ch-'0');ch=getchar();}
	return r*w;
}

const int N = 100005;


int head[N];
int nxt[N];
int to[N];
int deg[N];
int cnt;
int lastfa;

int sons;
int ans;
int ava;

int maxlea;
int sumlea;


void add(int u,int v) {
	cnt++;
	nxt[cnt] = head[u];
	to[cnt] = v;
	head[u] = cnt;
}
void dfs1(int now,int f){
	int c = 0;
	for (int w = head[now]; w != -1; w = nxt[w]) {
		c++;
		int v = to[w];
		
		if (v == f) continue;
		
		dfs1(v,now);
	}
	deg[now] = c;
	
}


int dfs2(int now,int f){
	int c = 0;
	int leaves = 0;
	for (int w = head[now]; w != -1; w = nxt[w]) {

		c++;
		int v = to[w];
		
		if (v == f) continue;
		
		int k = dfs2(v,now);
		if (k == 1) {
			leaves++;
		}
		
	}
	if (leaves > 0) {
		ava++;
		sumlea += leaves;
		maxlea = max(leaves,maxlea);
	}
	
//	if (leaves > 0){
//		if (sons == 0) {
//			sons += leaves;
//		} else {
//			if (sons >= leaves){
//				sons -= leaves;
//				ans += leaves;
//			} else {
//				ans += sons;
//				sons = leaves - sons;
//			}
//			ava = true;
//		}
//		lastfa = now;
//	}
	
	return c;
}


int main(){
	int T = read();
	int n = 0;
	int u,v;
	cnt = 0;
	memset(head,-1,sizeof(head));
	while(T--) {
		maxlea = -1;
		sumlea = 0;
		for (int i = 0; i <= n; ++i) {
			head[i] = -1;
		}
//		for (int i = 0; i < cnt+1; ++i) {
//			nxt[i] = -1;
//			to[i] = -1;
//		}
//		memset(head,-1,sizeof(head));
		cnt = 0;
		n = read();
		for (int i = 0; i < n-1; ++i) {
			u = read();
			v = read();
			add(u,v);
			add(v,u);
		}
		
		ans = 0;
		sons = 0;
		ava = 0;
		dfs1(1,-1);
		
//		return 0;
		
		for (int i = 1; i <= n; ++i) {
			if (deg[i] != 1) {
				int tmp = dfs2(i,-1);
				break;
			}
		}
		
		
		if (sumlea % 2 == 0){
			if (maxlea > sumlea / 2) {
				ans = (sumlea-maxlea) + maxlea-(sumlea-maxlea);
			} else {
				ans = sumlea-maxlea*2 + maxlea;
			}
		} else {
			if (maxlea > sumlea / 2) {
				ans = (sumlea-maxlea) + maxlea-(sumlea-maxlea);
			} else {
				ans = sumlea-maxlea*2 + maxlea;
			}
		}
		
		
		if (ava <= 1) {
			printf("-1\n");
		} else {
			printf("%d\n", ans);
		}
		
		
	}	

	
	return 0;
}