#include <bits/stdc++.h>

#define fastio ios::sync_with_stdio(false), cin.tie(0), cout.tie(0)

typedef double ff;
typedef long long int ll;
typedef unsigned long long int ull;
using namespace std;

typedef pair<ll, ll> pii;

const int N = 1e6 + 10, M = 1e7, base = 131;

typedef struct node {
	int x, y;
} node;

int dx[4] = {0, 0, -1, 1}, dy[4] = {1, -1, 0, 0};

void solve()
{
	int n, m;
	cin >> n >> m;
	
	vector<vector<char> > s(n + 1, vector<char>(m + 1));
	int cnt = 0;
	for(int i = 1; i <= n; i ++ ) {
		for(int j = 1; j <= m; j ++ ) {
			cin >> s[i][j];
			if(s[i][j] == 'W') cnt ++;
		}
	}
	
	if(s[1][1] == 'B' || s[n][m] == 'B') {
		cout << 'J' << '\n';
		return ;
	}
	
	vector<vector<bool> > vis(n + 1, vector<bool> (m + 1));
	
	queue<node> q;
	q.push({1, 1});
	
	vis[1][1] = true;
	
	while(q.size()) {
		auto t = q.front();
		q.pop();
		
		for(int i = 0; i < 4; i ++ ) {
			int x = t.x + dx[i], y = t.y + dy[i];
			if(x >= 1 && x <= n && y >= 1 && y <= m && !vis[x][y] && s[x][y] == 'W') {
				vis[x][y] = true;
				q.push({x, y});
			}		
		}
	}
	
	if(!vis[n][m]) {
		cout << 'J' << '\n';
		return ;
	}
	
	int have = cnt - (n + m - 1);
	if(have & 1) {
		cout << 'I' << '\n';
	} else {
		cout << 'J' << '\n';
	}
}

int main()
{
	fastio;

	int t = 1;
	cin >> t;

	while( t -- ) solve();
}