#include <bits/stdc++.h>
using namespace std;

namespace SOL {

using i64 = long long;
void debug(const char *msg, ...) {
#ifdef CLESIP
    va_list arg;
    static char pbString[512];
    va_start(arg,msg);
    vsprintf(pbString,msg,arg);
    cerr << "[DEBUG] " << pbString << "\n";
    va_end(arg);
#endif    
}
template<typename T, typename L>
bool chkmax(T &x, L y) { if (x < y) return x = y, true; return false; }
template<typename T, typename L>
bool chkmin(T &x, L y) { if (y < x) return x = y, true; return false; }

const int N = 110;
int n, st, ans[N];
bool g[N][N], vis[N];
char s[N];

void insert(int len, int pos, int val) {
	static int tmp[N];
	for (int i = pos; i <= len; i ++)
		tmp[i] = ans[i];
	ans[pos] = val;
	for (int i = pos + 1; i <= len + 1; i ++)
		ans[i] = tmp[i - 1];
}

void solve(int kase) {
	cout << "Case #" << kase << ": ";
	cin >> n >> st; st += 1;
	for (int i = 1; i <= n; i ++)
		vis[i] = false;
	for (int i = 1; i <= n; i ++) {
		cin >> (s + 1);
		for (int j = 1; j <= n; j ++) {
			if (s[j] == 'Y')
				g[j][i] = 1;
			else
				g[j][i] = 0;
		}
	}
	ans[1] = st; vis[st] = 1;
	for (int t = 1; t < n; t ++) {
		int cur = -1, pos = -1;
		for (int i = 1; i <= n && cur == -1; i ++) if (!vis[i]) {
			if (g[i][ans[1]]) {
				cur = i, pos = 1;
				break;
			}
			for (int j = 2; j <= t; j ++) {
				if (g[i][ans[j]]) {
					cur = i, pos = j;
					break;
				}
			}
		}
		if (cur == -1) {
			cout << "IMPOSSIBLE\n";
			return;
		}
		vis[cur] = 1;
		insert(t, pos, cur);
		// debug("t: %d pos: %d cur: %d", t, pos, cur);
	}
	for (int i = 1; i <= n; i ++)
		cout << ans[i] - 1 << " \n"[i == n];
}

}
int main() {
	ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	int tt; cin >> tt;
	for (int t = 1; t <= tt; t ++)
		SOL::solve(t);
	return 0;
}