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

const int dx[4] = {1, -1, 0, 0};
const int dy[4] = {0, 0, 1, -1};
const int N = 1005;

queue < pair <int, int> > q;
char c[N][N];
int vis[N][N];
int T, n, m;

int main() {
	scanf("%d", &T);
	while (T--) {
		memset(vis, 0, sizeof(vis));
		scanf("%d%d", &n, &m);
		int cnt = 0;
		for (int i = 1; i <= n; i++) {
			scanf("%s", c[i] + 1);
			for (int j = 1; j <= m; j++) cnt += (c[i][j] == 'W');
		}
		if (c[1][1] == 'W') {
			vis[1][1] = 1; q.push(make_pair(1, 1));
		}
		while (!q.empty()) {
			pair <int, int> t = q.front(); q.pop();
			for (int d = 0; d < 4; d++) {
				int x = t.first + dx[d];
				int y = t.second + dy[d];
				if (x < 1 || y < 1 || x > n || y > m || c[x][y] == 'B' || vis[x][y]) continue;
				vis[x][y] = 1; q.push(make_pair(x, y));
			}
		}
		if (!vis[n][m]) {
			printf("J\n");
		} else if ((cnt - (n + m - 1)) % 2) {
			printf("I\n");
		} else {
			printf("J\n");
		}
	}
	return 0;
}