#include <bits/stdc++.h>
using namespace std;
using ll = long long;
// const ll MOD = 1e9+7;

#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()

void solve() {
	int n; cin >> n;
	vector<int> signs(n);
	vector<vector<int>> g(n);
	for (int i = 0; i < n; i++) {
		cin >> signs[i];
	}
	
	int u, v;
	for (int i = 0; i < n-1; i++) {
		cin >> u >> v;
		u--; v--;
		g[u].push_back(v);
		g[v].push_back(u);
	}
	
	vector<vector<int>> res;
	for (int i = 0; i < n; i++) {
		vector<int> keres;
		for (int j : g[i]) {
			if (signs[i] == -1 && signs[j] == -1) {
				vector<int> x = {i+1, j+1};
				res.push_back(x);
			}
			if (signs[i] == 1 && signs[j] == -1) keres.push_back(j);
		}
		if (keres.size() > 1) {
			vector<int> x = {keres[0]+1, i+1, keres[1]+1};
			res.push_back(x);
		}
	}
	if ((int) res.size() == 0) {
		cout << "IGEN\n";
	} else {
		cout << "NEM\n";
		cout << res[0].size() << "\n";
		for (int i : res[0]) cout << i << " ";
		cout << "\n";
	}
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t; cin >> t;
    while (t--) solve();

    return 0;
}