/*
ID: bqi3431
PROG: ~
LANG: C++11 
*/

#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/rope>

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
 
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= (a); i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto& a : x)

#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound

#define sz(x) (int)x.size()
#define beg(x) x.begin()
#define en(x) x.end()
#define all(x) beg(x), en(x)
#define resz resize

const int MOD = 1000000007; // 998244353
const ll INF = 1e18;
const int MX = 200005;
const ld PI = 4*atan((ld)1);

template<class T> void ckmin(T &a, T b) { a = min(a, b); }
template<class T> void ckmax(T &a, T b) { a = max(a, b); }

namespace input {
    template<class T> void re(complex<T>& x);
    template<class T1, class T2> void re(pair<T1,T2>& p);
    template<class T> void re(vector<T>& a);
    template<class T, size_t SZ> void re(array<T,SZ>& a);

    template<class T> void re(T& x) { cin >> x; }
    void re(double& x) { string t; re(t); x = stod(t); }
    void re(ld& x) { string t; re(t); x = stold(t); }
    template<class Arg, class... Args> void re(Arg& first, Args&... rest) { 
        re(first); re(rest...); 
    }

    template<class T> void re(complex<T>& x) { T a,b; re(a,b); x = cd(a,b); }
    template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.f,p.s); }
    template<class T> void re(vector<T>& a) { F0R(i,sz(a)) re(a[i]); }
    template<class T, size_t SZ> void re(array<T,SZ>& a) { F0R(i,SZ) re(a[i]); }
}

using namespace input;

namespace output {
    template<class T1, class T2> void pr(const pair<T1,T2>& x);
    template<class T, size_t SZ> void pr(const array<T,SZ>& x);
    template<class T> void pr(const vector<T>& x);
    template<class T> void pr(const set<T>& x);
    template<class T1, class T2> void pr(const map<T1,T2>& x);

    template<class T> void pr(const T& x) { cout << x; }
    template<class Arg, class... Args> void pr(const Arg& first, const Args&... rest) { 
        pr(first); pr(rest...); 
    }

    template<class T1, class T2> void pr(const pair<T1,T2>& x) { 
        pr("{",x.f,", ",x.s,"}"); 
    }
    template<class T> void prContain(const T& x) {
        pr("{");
        bool fst = 1; for (const auto& a: x) pr(!fst?", ":"",a), fst = 0; // const needed for vector<bool>
        pr("}");
    }
    template<class T, size_t SZ> void pr(const array<T,SZ>& x) { prContain(x); }
    template<class T> void pr(const vector<T>& x) { prContain(x); }
    template<class T> void pr(const set<T>& x) { prContain(x); }
    template<class T1, class T2> void pr(const map<T1,T2>& x) { prContain(x); }
    
    void ps() { pr("\n"); }
    template<class Arg> void ps(const Arg& first) { 
        pr(first); ps(); // no space at end of line
    }
    template<class Arg, class... Args> void ps(const Arg& first, const Args&... rest) { 
        pr(first," "); ps(rest...); // print w/ spaces
    }
}

using namespace output;

namespace io {
    void setIn(string s) { freopen(s.c_str(),"r",stdin); }
    void setOut(string s) { freopen(s.c_str(),"w",stdout); }
    void setIO(string s = "") {
        ios_base::sync_with_stdio(0); cin.tie(0); // fast I/O
        if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
    }
}

using namespace io;

template<class T> T invGeneral(T a, T b) {
    a %= b; if (a == 0) return b == 1 ? 0 : -1;
    T x = invGeneral(b,a); 
    return x == -1 ? -1 : ((1-(ll)b*x)/a+b)%b;
}

template<class T> struct modular {
    T val; 
    explicit operator T() const { return val; }
    modular() { val = 0; }
    template<class U> modular(const U& v) {
        val = (-MOD <= v && v <= MOD) ? v : v % MOD;
        if (val < 0) val += MOD;
    }
    friend ostream& operator<<(ostream& os, const modular& a) { return os << a.val; }
    friend bool operator==(const modular& a, const modular& b) { return a.val == b.val; }
    friend bool operator!=(const modular& a, const modular& b) { return !(a == b); }

    modular operator-() const { return modular(-val); }
    modular& operator+=(const modular& m) { if ((val += m.val) >= MOD) val -= MOD; return *this; }
    modular& operator-=(const modular& m) { if ((val -= m.val) < 0) val += MOD; return *this; }
    modular& operator*=(const modular& m) { val = (ll)val*m.val%MOD; return *this; }
    friend modular exp(modular a, ll p) {
        modular ans = 1; for (; p; p /= 2, a *= a) if (p&1) ans *= a;
        return ans;
    }
    friend modular inv(const modular& a) { return invGeneral(a.val,MOD); } 
    // inv is equivalent to return exp(b,b.mod-2) if prime
    modular& operator/=(const modular& m) { return (*this) *= inv(m); }
    
    friend modular operator+(modular a, const modular& b) { return a += b; }
    friend modular operator-(modular a, const modular& b) { return a -= b; }
    friend modular operator*(modular a, const modular& b) { return a *= b; }
    
    friend modular operator/(modular a, const modular& b) { return a /= b; }
};

typedef modular<int> mi;
typedef pair<mi,mi> pmi;
typedef vector<mi> vmi;
typedef vector<pmi> vpmi;

template<int SZ> struct TopoSort {
    int N, in[SZ];
    vi res, adj[SZ];

    void addEdge(int x, int y) { adj[x].pb(y), in[y] ++; 
    // ps("ZZ",x,y); 
        
    }

    bool sort(int _N) {
        N = _N; queue<int> todo;
        FOR(i,1,N+1) if (in[i] == 0) todo.push(i);
        while (sz(todo)) {
            int x = todo.front(); todo.pop(); res.pb(x);
            trav(i,adj[x]) {
                in[i] --;
                if (!in[i]) todo.push(i);
            }
        }
        return sz(res) == N;
    }
};

int T,N, pre[2][51];
set<int> adj[2][51];
int ans = MOD;

void dfs(int ind, int a, int b) {
    // ps("HA",ind,a,b,pre[ind][a]);
    trav(t,adj[ind][a]) if (t != b) {
        pre[ind][t] = a;
        dfs(ind,t,a);
    }
}

void test(int x, int res = 0) {
    //ps("WUT",x);
    pre[0][x] = pre[1][x] = 0;
    dfs(0,x,0); dfs(1,x,0);
    /*ps(adj[0][1],adj[0][2],adj[0][3]);
    ps("----");*/
    TopoSort<51> T = TopoSort<51>(); FOR(i,1,N+1) assert(!T.in[i]);
    vector<bool> bad(N+1);
    FOR(i,1,N+1) if (pre[0][i] != pre[1][i]) bad[i] = 1;
    FOR(i,1,N+1) if (bad[i]) {
        FOR(j,1,N+1) if (!bad[j] && pre[0][j] == i) return;
        FOR(j,1,N+1) if (bad[j]) if (pre[1][j] == i) T.addEdge(i,j);
        FOR(j,1,N+1) if (bad[j]) if (pre[0][j] == i) T.addEdge(j,i);
    }
    if (!T.sort(N)) {
       // ps("??",x,T.res,bad);
        return;
    }
    // ps("HA",x,T.res,bad);
    FOR(i,1,N+1) if (bad[i]) res ++;
    ckmin(ans,res);
}

void solve() {
    re(N); ans = MOD;
    F0R(i,2) FOR(j,1,N+1) adj[i][j].clear();
    F0R(i,2) F0R(j,N-1) {
        int a,b; re(a,b);
        adj[i][a].insert(b), adj[i][b].insert(a);
    }
    FOR(i,1,N+1) if (sz(adj[0][i]) == 1) {
        int x = *adj[0][i].begin();
        adj[0][i].erase(x), adj[0][x].erase(i);
        FOR(j,1,N+1) {
            adj[0][i].insert(j), adj[0][j].insert(i);
            test(i,1);
            adj[0][i].erase(j), adj[0][j].erase(i);
        }
        adj[0][i].insert(x), adj[0][x].insert(i);
    }
    // ps(ans);
    FOR(i,1,N+1) test(i);
    if (ans == MOD) ps(-1);
    else ps(ans);
}

int main() {
    setIO(); re(T);
    F0R(i,T) solve();
}

/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?), set tle
    * do smth instead of nothing and stay organized
*/

Measured memory_bytes: 256