#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair <int, int> ii;
typedef vector <int> vi;
typedef vector <vi> vvi;
typedef vector <ii> vii;
typedef vector <vii> vvii;
#define endl '\n'
#define PB push_back
#define MP make_pair
#define fr first
#define sc second
#define OO (1000000000)         // ToDo
#define EPS (1e-9)              // ToDo
#define MOD (1000000007)        // ToDo
#define all(v) ((v).begin()),((v).end())
#define wt(x) cout<< #x <<" = "<<"\""<< (x) <<"\""<<endl
#define FASTIO ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
void read_file(bool outToFile = true){
#ifdef LOCAL_TEST
    freopen("in", "rt", stdin);
    if(outToFile)
    freopen("out", "wt", stdout);
#endif
}
//
const int MAXN = 100 * 1000 + 99;
//
int TC;
int n;
int W[MAXN];
vvi G;
ll dp[MAXN], depth[MAXN];
ll sub[MAXN];
int P[MAXN]; // parent array
ll S;
//
void DFS(int u=0, int p=-1){

    P[u] = p;
    depth[u] = p == -1? 0 : depth[p] + 1;

    sub[u] = 1;
    ll X = 0, Y = 0; // sizes of the left, right subtrees
    for(int i=0; i<G[u].size(); i++)
    {
        int v = G[u][i];
        if(v == p) continue;
        DFS(v, u);

        sub[u] += sub[v];
        if(X == 0)
            X = sub[v];
        else
            Y = sub[v];
    }
    ll Z = n-1 - X - Y; // size of other nodes

    dp[u] = X*Y + Y*Z + Z*X;    // paths that don't end at u
    dp[u] = dp[u] + n-1;        // adding n-1 paths which have u as an endpoint
    dp[u] = dp[u]*2;            // multiplying by 2 for the two directions
    dp[u] = dp[u] + 1;          // adding 1 for the path (u, u)
}
void solve(){
    // calculations
    DFS();

    // step one
    S = 0;
    for(int u=0; u<n; u++)
        S += W[u] * dp[u];

    if(S == 0)
    {
        printf("0\n");
        return;
    }

    // step two
    for(int u=0; u<n; u++)
    {
        if(S%dp[u] == 0) // dp[u] must be >= 1, no special cases
        {
            printf("1 ");
            printf("%d\n", u+1);
            //cerr << W[u] - S / dp[u] <<endl;
            return;
        }
    }

    // step three
    int cho = 0;
    for(int u=0; u<n; u++)
    {
        if(depth[cho] < depth[u])
            cho = u;
    }

    int u = cho, v = P[u];
    printf("2 ");
    printf("%d %d\n", u+1, v+1);

    assert(dp[u] == 2*n-1 && dp[v] == 6*n-11);
    assert(__gcd(dp[u], dp[v]) == 1); // because it's free
    //cerr<< S <<endl;
}
//
int main()
{
    //read_file();
    scanf("%d", &TC);
    while(TC--)
    {
        // reading input
        scanf("%d", &n);
        G.assign(n, vi());
        for(int u=0; u<n; u++)
            scanf("%lld", &W[u]);
        for(int i=0; i<n-1; i++)
        {
            int u, v;
            scanf("%d %d", &u, &v);
            --u;--v;
            G[u].PB(v);
            G[v].PB(u);
        }



        solve();
        //printf("\n");
    }
}