#include<iostream>
#include<vector>
#include<map>
#include<set>
#include<cassert>
#include<cassert>
#include<unordered_map>
#include<unordered_set>
#include<functional>
#include<queue>
#include<stack>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<sstream>
#include<iomanip>
#include<cstdio>
#include<cstdlib>
#include<numeric>
#include<random>
#include<chrono>
#include<bitset>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define eb emplace_back
#define xx first
#define yy second
#define sz(x) (int)(x).size()
#define gc getchar
#define IO ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define mp make_pair
#define ins insert
#ifndef ONLINE_JUDGE
# define LOG(x) (cerr << #x << " = " << (x) << endl)
#else
# define LOG(x) ((void)0)
#endif
using ll = long long;
using ull = unsigned long long ;
using ld = long double ;
using str = string;
using ordered_set=tree<pair<int,int>, null_type, less<pair<int,int>>, rb_tree_tag, tree_order_statistics_node_update>;
const double PI=acos(-1);
const ll INF = 1LL<<62;
const ll MINF = -(1LL<<62);
template<typename T> T getint() {
T val=0;
char c;
bool neg=false;
while((c=gc()) && !(c>='0' && c<='9')) {
neg|=c=='-';
}
do {
val=(val*10)+c-'0';
} while((c=gc()) && (c>='0' && c<='9'));
return val*(neg?-1:1);
}
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); uniform_int_distribution<int>(0, n-1)(rng)
const int MAXN=200001;
int n,t,j,k;
vector<int> adj[MAXN];
vector<int> distt, distj;
vector<int> bfs(int x) {
vector<int> dist(n+1, -1);
queue<pair<int,int>> q;
q.push({x, 0});
dist[x]=0;
while(!q.empty()) {
auto akt=q.front();q.pop();
for(auto i:adj[akt.first]) {
if(dist[i]==-1) {
dist[i]=akt.yy+1;
q.push({i, dist[i]});
}
}
}
return dist;
}
int vis[MAXN];
int explore(int jerry) {
if(distj[jerry]>=distt[jerry]-1 || vis[jerry]) return -1;
vis[jerry]=1;
int mx=distt[jerry];
for(auto i:adj[jerry]) {
mx=max(mx, explore(i));
}
return mx;
}
int main() {
IO;
int T;
cin>>T;
while(T--) {
cin>>n>>t>>j>>k;
for(int i=1;i<=n;++i) {
adj[i].clear();
vis[i]=0;
}
for(int i=1;i<n;++i) {
int a,b;
cin>>a>>b;
adj[a].pb(b);
adj[b].pb(a);
}
vector<int> dist1=bfs(1);
int furthest=max_element(all(dist1))-dist1.begin();
vector<int> distf=bfs(furthest);
int diameter=*max_element(all(distf));
bool can_catch=false;
can_catch|=diameter<=2*k;
distt=bfs(t);
distj=bfs(j);
int mx=explore(j);
can_catch|=mx<=k;
cout<<(can_catch?"IGEN":"NEM")<<"\n";
}
return 0;
}