#include <iostream>
#include <cstring>

#define MAX_N (50 + 5)

using namespace std;

struct Edge
{
    int to;
    int next;
};

const long long lim = 2000000000LL;
int T;
int n, root;
char l[MAX_N][MAX_N];
int h[MAX_N];
Edge e[MAX_N];
int cnt;
int dep[MAX_N];
long long ans;

void Init()
{
    memset(h, 0, sizeof h);
    memset(e, 0, sizeof e);
    memset(dep, 0, sizeof dep);
    cnt = ans = 0;
    return;
}

inline void Make_Edge(int u, int v)
{
    e[++cnt].to = v;
    e[cnt].next = h[u];
    h[u] = cnt;
    return;
}

void Build(int u, int p)
{
    for(register int v = 1; v <= n; ++v)
    {
        if(l[u][v] != ‘Y‘ || v == p) continue;
        Make_Edge(u, v);
        Build(v, u);
        dep[u] = max(dep[u], dep[v]);
    }
    ++dep[u];
    return;
}

void DFS(int u, long long val)
{
    int v, p = 0;
    for(register int i = h[u]; i; i = e[i].next)
    {
        v = e[i].to;
        if(dep[p] < dep[v]) p = v;
    }
    if(!p)
    {
        ans += val;
        return;
    }
    DFS(p, val << 1 | 1LL);
    for(register int i = h[u]; i; i = e[i].next)
    {
        v = e[i].to;
        if(p != v) DFS(v, 1LL);
    }
    return;
}

int main()
{
    cin >> T;
    while(T--) 
    {
        Init();
        cin >> n >> root;
        ++root;
        for(register int i = 1; i <= n; ++i)
        {
            cin >> l[i] + 1;
        }
        Build(root, -1);
        bool op = false;
        for(register int i = 1; i <= n; ++i)
        {
            if(!dep[i]) 
            {
                printf("-1\n");
                op = true;
                break;
            }
        }
        if(op) continue;
        DFS(root, 0);
        if(ans > lim) cout << "-1\n";
        else cout << ans << "\n";
    }
    return 0;
}