/*

首先对整个图bfs一次得到火焰燃烧的时刻表

之后在bfs搜路径时加一个火烧表的判断

坑点在于：如果时刻表等于0应该是从未烧过。。。如果不加以区分就会wa

*/

#include <bits/stdc++.h>

#define scan(x) scanf("%d",&x)

#define M(x) memset(x,0,sizeof(x))

#define REF(i,n) for(int i=1;i<=n;i++)

using namespace std;

const int Max=1e3+;

char mat[Max][Max];

int book[Max][Max];

int vis[Max][Max];

int n,m,stx,sty;

struct node

{

    int x,y,step;

    node(){x=y=step=;}

    node(int xx,int yy,int ss):x(xx),y(yy),step(ss){}

};

int nex[][]={,,,,,-,-,};

queue<node>que1;

void bfs1()

{

    M(book);M(vis);

    node u,v;

    while(!que1.empty())

    {

        u=que1.front();

        que1.pop();

        for(int k=;k<;k++)

        {

            v.x=u.x+nex[k][];

            v.y=u.y+nex[k][];

            v.step=u.step+;

            if(v.x<||v.y<||v.x>n||v.y>m) continue;

            if(mat[v.x][v.y]=='#') continue;

            if(book[v.x][v.y]) continue;

            book[v.x][v.y]=v.step;

            que1.push(v);

        }

    }

}

int bfs2()

{

    M(vis);

    queue<node>que;

    node u,v;

    que.push(node(stx,sty,));

    vis[stx][sty]=;

    while(!que.empty())

    {

        u=que.front();

        que.pop();

        for(int k=;k<;k++)

        {

            v.x=u.x+nex[k][];

            v.y=u.y+nex[k][];

            v.step=u.step+;

            if(v.x<||v.y<||v.x>n||v.y>m) return v.step;

            if(book[v.x][v.y]!=&&book[v.x][v.y]<=v.step) continue;//book[i][j]!=0

            if(mat[v.x][v.y]=='#'||mat[v.x][v.y]=='F') continue;//不能把从未着火的点也排除

            if(vis[v.x][v.y]) continue;

            vis[v.x][v.y]=;

            que.push(v);

        }

    }

    return -;

}

int main()

{

    int T;

    for(scan(T);T;T--)

    {

        cin>>n>>m;getchar();

        while(!que1.empty()) que1.pop();

        REF(i,n)

        {

            REF(j,m)

            {

               scanf("%c",&mat[i][j]);

               if(mat[i][j]=='J') stx=i,sty=j;

               if(mat[i][j]=='F') que1.push(node(i,j,));

            }

            getchar();

        }

        bfs1();

        int ans=bfs2();

        if(ans!=-) cout<<ans<<endl;

        else cout<<"IMPOSSIBLE"<<endl;

    }

    return ;

}