// Author: Klay Thompson
// Problem: D. 黑白
// Memory Limit: 1024 MB
// Time Limit: 1000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>

#define rep(i, j, k) for (int i = (j); i <= (k); ++i)
#define per(i, j, k) for (int i = (j); i >= (k); --i)
#define SZ(v) int((v).size())
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second
using ll = long long;
using pii = std::pair<int, int>;
using pll = std::pair<ll, ll>;

template<class T>inline void chkmn(T &x, T y) { if (y < x) x = y; }
template<class T>inline void chkmx(T &x, T y) { if (y > x) x = y; }

using namespace std;

const int maxn = 1010;

int dx[] = {0, -1, 0, 1};
int dy[] = {-1, 0, 1, 0};
int n, m, vis[maxn][maxn];
char s[maxn][maxn];

void dfs(int x, int y) {
  vis[x][y] = 1;
  rep (k, 0, 3) {
    int tx = x + dx[k], ty = y + dy[k];
    if (tx < 1 || tx > n || ty < 1 || ty > m) continue;
    if (s[tx][ty] == 'W' && !vis[tx][ty]) dfs(tx, ty);
  }
}

void work() {
  cin >> n >> m;
  rep (i, 1, n) cin >> (s[i] + 1);
  rep (i, 1, n) rep (j, 1, m) vis[i][j] = 0;
  if (s[1][1] == 'B') return cout << "J\n", void();
  dfs(1, 1);
  if (!vis[n][m]) return cout << "J\n", void();
  int cnt = 0;
  rep (i, 1, n) rep (j, 1, m) cnt += (s[i][j] == 'W');
  if ((cnt & 1) ^ ((n + m) & 1)) cout << "J\n";
  else cout << "I\n";
}

int main() {
  cin.tie(nullptr) -> ios::sync_with_stdio(false);
  int t; cin >> t;
  while (t--) work();
}