#include <bits/stdc++.h>
using namespace std;
int main() {
    int t; cin >> t;
    while (t--) {
        int n; cin >> n;
        vector<int> a(n+1);
        for (int i = 1; i <= n; i++) cin >> a[i];
        vector<vector<int>> g(n+1);
        for (int i = 0; i < n-1; i++) {
            int a,b; cin >> a >> b;
            g[a].push_back(b);
            g[b].push_back(a);
        }
        bool f = false;
        for (int i = 1; i <= n; i++) {
            for (int x : g[i]) {
                if (a[i] == -1 && a[x] == -1) {
                    cout << "NEM\n2\n" << i << ' ' << x << '\n';
                    f = true;
                    break;
                }
                else if (g[x].size() >= 2 && a[i] == -1 && a[x] == 1) {
                    for (int y : g[x]) {
                        if (a[y] == -1 && y != i) {
                            cout << "NEM\n3\n" << i << ' ' << x << ' ' << y << '\n';
                            f = true;
                            break;
                        }
                    }
                    if (f) break;
                }
            }
            if (f) break;
        }
        if (!f) cout << "IGEN\n";
    }
}