#include <bits/stdc++.h>
#define rep(i,n) for ((i)=1;(i)<=(n);(i)++)
#define foreach(c,itr) for (__typeof((c).begin()) itr=(c).begin();itr!=(c).end();++itr)
using namespace std;
int t,n,m,i,j,fa1[55],fa2[55],deg[55],ans,isl[55];
vector<int> ga[55],gb[55];
void dfs1(int x,int fa){
	fa1[x]=fa;
	foreach(ga[x],i){
		if(*i!=fa) dfs1(*i,x);
	}
}
void dfs2(int x,int fa){
	fa2[x]=fa;
	foreach(gb[x],i){
		if(*i!=fa) dfs2(*i,x);
	}
}
void solve(int x,int y){
	dfs1(y,0);dfs2(x,0);
	fa1[y]=x;fa1[x]=0;
	memset(deg,0,sizeof(deg));
	int i,j,c=0;
	rep(i,n) if(i!=x) deg[fa1[i]]++;
	rep(i,n) if(i!=x&&fa1[i]!=fa2[i]) c++;
	rep(i,c){
		rep(j,n){
			if(j==x) continue;
			if(fa1[j]==fa2[j]) continue;
			if(deg[j]) continue;
			if(fa1[fa2[j]]!=fa2[fa2[j]]) continue;
			break;
		}
		if(j>n) return;
		deg[fa1[j]]--;
		deg[fa2[j]]++;
		fa1[j]=fa2[j];
	}
	ans=min(ans,c+1);
}
int main(){
//	freopen("1.in","r",stdin); 
	cin>>t;
	while(t--){
		cin>>n;
		rep(i,n){
			isl[i]=0;
			ga[i].clear();
			gb[i].clear();
		}
		rep(i,n-1){
			int x,y;
			cin>>x>>y;
			ga[x].push_back(y);
			ga[y].push_back(x);
			isl[x]++;isl[y]++;
		}
		rep(i,n-1){
			int x,y;
			cin>>x>>y;
			gb[x].push_back(y);
			gb[y].push_back(x);
		}
		int f=1;
		dfs1(1,0);dfs2(1,0);
		rep(i,n)if(fa1[i]!=fa2[i]) f=0;
		if(f){
			puts("0");
			continue; 
		}
		ans=0x3f3f3f3f;
		rep(i,n)if(isl[i]==1)rep(j,n)if(i!=j){
			solve(i,j);
		}
		if(ans==0x3f3f3f3f){
			puts("-1");
		}
		else{
			printf("%d\n",ans);
		}
	}
	return 0;
}