#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], in[N];
char s[N];

void dfs(int x) {
	if (vis[x])
		return;
	vis[x] = 1;
	for (int i = 1; i <= n; i ++)
		if (g[i][x] && !in[i])
			dfs(i);
}

bool check(int pre) {
	for (int i = 1; i <= n; i ++)
		vis[i] = 0;
	vis[pre] = 1;
	dfs(st);
	for (int i = 1; i <= n; i ++)
		if (!vis[i] && !in[i] && !g[i][pre])
			return 0;
	return 1;
}

void solve(int kase) {
	cout << "Case #" << kase << ": ";
	cin >> n >> st; st += 1;
	for (int i = 1; i <= n; i ++)
		vis[i] = in[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;
		}
	}
	dfs(st);
	for (int i = 1; i <= n; i ++)
		if (!vis[i]) {
			cout << "IMPOSSIBLE\n";
			return;
		}
	int pre = -1;
	for (int i = 1; i <= n; i ++) {
		for (int j = 1; j <= n; j ++) if (!in[j]) {
			if (pre != -1 && j == st && g[st][pre])
				continue;
			int cur = pre;
			if (cur == -1 || g[cur][j])
				cur = j;
			in[j] = 1;
			if (check(cur)) {
				pre = cur;
				ans[i] = j;
				break;
			}
			in[j] = 0;
		}
	}
	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;
}