#include <bits/stdc++.h>
using namespace std;

void solve() {
    int n;
    cin >> n;
    vector<int> tisztas(n);
    vector<int> a[n], sztas;
    for (int i = 0; i < n; i++) {
        cin >> tisztas[i];
        if (tisztas[i] == -1) sztas.push_back(i);
    }
    for (int i = 0; i < n-1; i++) {
        int x, y;
        cin >> x >> y;
        a[x-1].push_back(y-1);
    }
    //for (int i = 0; i < sztas.size(); i++) cout << sztas[i] << " ";

    for (int i = 0; i < sztas.size(); i++) {
        for (int j = 0; j < a[sztas[i]].size(); j++) {
            if (tisztas[a[sztas[i]][j]] == -1) {
                cout << "NEM" << endl << 2 << endl;
                cout << sztas[i]+1 << " " << a[sztas[i]][j]+1 << endl;
                return;
            } else {
                for (int k = 0; k < a[a[sztas[i]][j]].size(); k++) {
                    if (tisztas[a[a[sztas[i]][j]][k]] == -1) {
                        cout << "NEM" << endl << 3 << endl;
                        cout << sztas[i]+1 << " " << a[sztas[i]][j]+1 << " " << a[a[i][j]][k]+1 << endl;
                        return;
                    }
                }
            }
        }
    }
    cout << "IGEN" << endl;

}
int main() {
    int t;
    cin >> t;
    while(t--) {
        solve();
    }

}