#include <bits/stdc++.h>
using namespace std;
#define cout(st) for(auto& i : st) cout << i << " "; cout << "\n"
#define cin_2d(vec, n, m) for(int i=0; i<n; i++) for(int j=0; j<m && cin >> vec[i][j]; j++);
#define cout_2d(vec, r, c) for(int i=0; i<r; i++, cout << "\n") for(int j=0; j<c && cout << vec[i][j] << ""; j++)
#define cout_map(mp) for(auto& [f, s] : mp) cout << f << " : " << s << "\n"
#define matrix(grid, n, m) vector < vector <int> > grid(n, vector <int> (m));
#define Time cerr << "Time Taken: " << (float)clock() / CLOCKS_PER_SEC << " Secs" << "\n";
#define ceil(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
#define fixed(n) cout << fixed << setprecision(n)
#define Num_of_Digits(n) ((int)log10(n)+1)
#define getline(s) getline(cin >> ws, s)
#define to_decimal(bin) stoll(bin, nullptr, 2)
#define rall(s) s.rbegin(), s.rend()
#define all(s) s.begin(), s.end()
#define sz(x) int(x.size())
#define Pair pair <int, int>
#define fi first
#define se second
#define ll long long
#define PI acos(-1)
#define Mod 1'000'000'007
#define INF 2'000'000'000
#define EPS 1e-9
#define endl cout << "\n";

template < typename T = int > istream& operator >> (istream &in, vector < T > &v) {
    for (auto &x: v) in >> x;
    return in;
}

template < typename T = int > ostream& operator << (ostream &out, const vector < T > &v) {
    for (const T &x: v) out << x << ' ';
    return out;
}

void Anwar_Rizk(){
  ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
  // #ifndef ONLINE_JUDGE    // Anwar Rizk 🥇🖤
  //   freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
  // #endif
}

double n, x, y, sum;
vector < int > temp;

bool subsets(vector < int > v, int n){
  for(int i = 0; i < (1 << n); i++){
    temp.clear();
    int s = 0;
    for(int j = 0; j < n; j++){
      if(i & (1 << j)) temp.push_back(v[j]), s += v[j];
    }
    if(s / (sum - s) == x / y){
      cout << "POSSIBLE\n";
      cout << sz(temp) << "\n";
      cout << temp;
      endl
      return true;
    }
  }
  return false;
}

void solve(){
    cin >> n >> x >> y;
    vector < int > v(n);
    iota(all(v), 1);
    sum = n * (n + 1) / 2;
    if(!subsets(v, n)){
      cout << "IMPOSSIBLE\n";
    }
}

int main()
{   Anwar_Rizk();

    int t = 1, tests = 1;
    cin >> t;
    while(t--){
      cout << "Case #" << tests++ << ": ";
      solve();
    }

  return 0;
}