#include<bits/stdc++.h>
using namespace std;
int n,m;
char ch[1005][1005];
int dis[1005][1005];
int dx[]={0,0,1,-1};
int dy[]={1,-1,0,0};
void solve(){
	cin>>n>>m;
	int s=0;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>ch[i][j];
			dis[i][j]=-1;
			if(ch[i][j]=='W') s++;
		}
	}
	queue<pair<int,int> > q;
	q.push(make_pair(1,1));
	dis[1][1]=1;
	while(!q.empty()){
		pair<int,int> now=q.front();q.pop();
		for(int i=0;i<4;i++){
			pair<int,int> nxt=now;
			nxt.first+=dx[i];
			nxt.second+=dy[i];
			int x=nxt.first,y=nxt.second;
			if(x<1||x>n||y<1||y>m) continue;
			if(dis[x][y]!=-1) continue;
			if(ch[x][y]=='B') continue;
			dis[x][y]=dis[now.first][now.second]+1;
			q.push(nxt);
		}
	}
	if(dis[n][m]==-1){
		cout<<"J\n";
		return ;
	}
	s-=dis[n][m];
	if(s&1) cout<<"I\n";
	else cout<<"J\n";
}
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	int tt;cin>>tt;
	while(tt--){
		solve();
	}
}