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

int main() {
    int t; cin >> t;
    while(t--) {
        int n; cin >> n;
        vector<int> v(n+1);
        for (int i = 1; i <= n; i++) cin >> v[i];
        vector<vector<int>> szomszedsagi(n+1);
        for(int i = 0; i < n - 1; i++) {
            int a, b; cin >> a >> b;
            szomszedsagi[a].push_back(b);
            szomszedsagi[b].push_back(a);
        } bool b = false; 
        for(int i = 1; i <= n; i++) {
            for(int y : szomszedsagi[i]) {
                if(v[y] == -1 && v[i] == -1) {                    
                    b = true;
                    cout << "NEM" << "\n" << 2 << "\n" << i << " " << y << "\n";
                    break;
                } else if(v[i] == -1 && v[y] == 1 && szomszedsagi[y].size() >= 2) {
                    for(int z : szomszedsagi[y]) {
                        if(v[z] == -1 && z != i) {                            
                            b = true;
                            cout << "NEM" << "\n" << 3 << "\n" << i << " " << y << " " << z << "\n";
                            break;
                        }
                    } if(b == true) break; 
                }
            }
            if(b == true) break;
        } if(b == false) cout << "IGEN" << "\n";
    }
}