// MagicDark
#include <bits/stdc++.h>
#define debug cerr << "\033[32m[" << __LINE__ << "]\033[0m "
#define SZ(x) ((int) x.size() - 1)
#define all(x) x.begin(), x.end()
#define ms(x, y) memset(x, y, sizeof x)
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define DF(i, x, y) for (int i = (x); i >= (y); i--)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template <typename T> T& chkmax(T& x, T y) {return x = max(x, y);}
template <typename T> T& chkmin(T& x, T y) {return x = min(x, y);}
template <typename T> T& read(T &x) {
	x = 0; int f = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') f = -f;
	for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
	return x *= f;
}
const int N = 2e3 + 10;
int n, pos, deg[N], col[N];//, w[N];
bool vis[N];
pair <int, int> p[N];
bool a[N][N];//, g[N];
void zhk() {
	read(n), read(pos)++;
	// debug << n << " " << pos << endl;
	F(i, 1, n) {
		// g[i] = false;
		a[i][0] = true;
		deg[i] = 0;
		F(j, 1, n) {
			char ch;
			do {
				ch = getchar();
			} while (ch != '-' && ch != 'N' && ch != 'Y');
			deg[i] += (a[i][j] = ch == 'Y');
		}
		p[i] = make_pair(deg[i], i);
	}
	sort(p + 1, p + n + 1);
	int s = 0, cnt = 1;
	F(i, 1, n) {
		s += p[i].first;
		col[p[i].second] = cnt;
		if (i != n && s == i * (i - 1) / 2) {
			cnt++;
			// g[i] = true;
		}
	}
	if (col[pos] != cnt) {
		cout << "IMPOSSIBLE\n";
		return;
	}
	// vector <int> ta;
	// priority_queue <int, vector <int>, greater <int>> tb;
	// F(i, 1, n)
	// 	if (col[pos] == cnt) ta.push_back(i);
	// 	else tb.push(i);
	// for (int i: ta) deg[i] -= tb.size();
	F(i, 1, n) vis[i] = false;
	int cur = 0;
	vector <int> ans;
	while (!vis[pos]) {
		F(i, 1, n) if (!vis[i]) {
			int pp;
			if (a[cur][i]) pp = cur;
			else pp = i;
			if (i == pos) {
				if (pp != pos) continue;
				bool flag = true;
				F(j, 1, n)
					if (!vis[j] && j != i) {
						if (a[j][i]) {
							flag = false;
							break;
						}
					}
				if (flag) {
					vis[i] = true;
					ans.push_back(i);
					break;
				}
			} else {
				int tot = 0;
				F(j, 1, n)
					if (!vis[j] && j != i) p[++tot] = make_pair(deg[j] - a[j][i], j);
				// if (!tot) {
				// 	ans.push_back(i);
				// 	break;
				// }
				sort(p + 1, p + tot + 1);
				int cnt = 1, s = 0;
				F(j, 1, tot) {
					s += p[j].first;
					col[p[j].second] = cnt;
					if (j != tot && s == j * (j - 1) / 2) cnt++;
					// debug << " -> " << p[j].first << ' ' << cnt << endl;
				}
				bool flag = true;
				F(j, 1, n) if (!vis[j] && j != i && col[j] > col[pos]) {
					// debug << " -> " << j << endl;
					if (a[j][pp]) {
						flag = false;
						break;
					}
				}
				// debug << "! " << i << " " << flag << " " << pp << endl;
				// F(j, 1, n)
				// 	if (!vis[j] && j != i) debug << col[j] << endl;
				if (flag) {
					F(j, 1, n)
						if (!vis[j] && j != i) deg[j] -= a[j][i];
					vis[i] = true;
					ans.push_back(i);
					break;
				}
			}
			// if (col[pos] == cnt) {
			// 	while (tb.size() && tb.top() < ta[i - 1]) {
			// 		ans.push_back(tb.top());
			// 		tb.pop();
			// 	}
			// 	ans.push_back(ta[i - 1]);
			// 	vector <int> nta;
			// 	F(j, 1, ta.size()) if (j != i) {
			// 		if (col[ta[j - 1]] == cnt) nta.push_back(ta[j - 1]);
			// 		else tb.insert(ta[j - 1]);
			// 	}
			// 	break;
			// }
		}
	}
	F(i, 1, n)
		if (!vis[i]) ans.push_back(i);
	for (int i: ans) cout << i - 1 << ' '; cout << '\n';
}
signed main() {
	int t; read(t);
	F(i, 1, t) {
		printf("Case #%d: ", i);
		zhk();
	}
	return 0;
}