int main(int argc, char const *argv[]) {
ios::sync_with_stdio(false);
int n, m;
DisjointSet *D;
while (cin >> n >> m && n != 0) {
D = new DisjointSet(n);
for (int i = 0; i < m; ++i) {
int k;
cin >> k;
int a = -1, b;
for (int j = 0; j < k; ++j) {
cin >> b;
if (a != -1) {
D->Union(a, b);
}
a = b;
}
}
int suspect = 0;
for (int i = 0; i < n; ++i) {
suspect += D->Find(i) == D->Find(0);
}
cout << suspect << endl;
}
return 0;
}
int main(int argc, char const *argv[]) {
ios::sync_with_stdio(false);
int t;
DisjointSet *D;
cin >> t;
for (int cs = 0; cs < t; ++cs) {
int n, m;
cin >> n >> m;
D = new DisjointSet(n);
for (auto& a : D->total) {
cin >> a;
}
for (int i = 0; i < m; ++i) {
int a, b;
cin >> a >> b;
D->Union(a, b);
}
string ans = "POSSIBLE";
for (int i = 0; i < n; ++i) if (D->Find(i) == i && D->total[i] != 0) {
ans = "IMPOSSIBLE";
}
cout << ans << endl;
}
return 0;
}