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

void solve() {
    int n;
    cin >> n;
    vector<int> t(n+1);
    for(int i = 1; i <= n; i++) {
        cin >> t[i];
    }

    vector<vector<int> > adj(n+1);

    for(int i = 1; i < n; i++) {
        int x, y;
        cin >> x >> y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }

    for(int i = 1; i <= n; i++) {
        if (t[i] == -1) {
            for(auto u : adj[i]) {
                if (t[u] == -1) {
                    cout << "NEM\n";
                    cout << 2 << '\n' << i << ' ' << u << '\n';
                    return;
                } else {
                    for(auto v : adj[u]) {
                        if (t[v] == -1) {
                            cout << "NEM\n";
                            cout << 3 << '\n' << i << ' ' << u << ' ' << v << '\n';
                            return;
                        }
                    }
                }
            }
        }
    }
    cout << "IGEN\n";

}

int main() {
	ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	int tt;
	cin >> tt;
	while(tt--) {
        solve();
	}


	return 0;
}