#include<bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < n; ++i)
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;

int n, targ;
string s[111];
bitset<111> g[111], rg[111];
vi ans;
bool in[111];
bool check(int u){
	bitset<111> q, done;
	q = 0, done = 0;
	q[targ] = done[targ] = 1;
	while(1){
		int i = (int)q._Find_first();
		if(i >= n) break;
		//cout << "  " << "bfs " << i << endl;
		q[i] = 0;
		if(in[i]) continue;
		q |= rg[i] & (~done);
		done |= rg[i];
	}
	if(!done[u]) return 0;
	done |= rg[u];
	bool ret = 1;
	rep(i, n) if(!in[i])
		ret &= done[i];
	//cout << "check " << u << " " << ret << endl;
	return ret;
}
bool search(int u){
	if(!check(u))
		return 0;
	//cout << "search " << u << ": ";
	//rep(i, (int)ans.size())
	//	cout << ans[i] << " ";
	//cout << "\n";
	if((int)ans.size() == n)
		return 1;
	for(int i = 0; i < n; ++i){
		if(in[i]) continue;
		in[i] = 1;
		ans.emplace_back(i);
		//cout << " " << u << " to " << i << endl;
		if(search(g[u][i] ? i : u)) return 1;
		ans.pop_back();
		in[i] = 0;
	}
	return 0;
}
void solve(){
	cin >> n >> targ;
	rep(i, n){
		cin >> s[i];
		rep(j, n)
			g[i][j] = (s[i][j] == 'N'), rg[i][j] = (s[i][j] == 'Y');
	}
	if(n == 1){
		cout << "0\n";
		return ;
	}
	memset(in, 0, sizeof(in));
	rep(i, n){
		ans.clear();
		in[i] = 1;
		ans.emplace_back(i);
		if(search(i)){
			rep(j, n)
				cout << ans[j] << " ";
			cout << "\n";
			return ;
		}
		in[i] = 0;
	}
	cout << "IMPOSSIBLE\n";
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);

	int T;
	cin >> T;
	rep(i, T){
		cout << "Case #" << i+1 << ": ";
		solve();
	}
	
	return 0;
}

// by zxb
// start coding at 13:19
// submission #1 at 13:45
// submission #2 at 13:49
// submission #3 at 13:52