1 #include <queue>
 2 #include <cstdio>
 3 #include <cstring>
 4 using namespace std;
 5
 6 const int inf = 0x3f3f3f3f;
 7 int T, r, c, ans, sx, sy;
 8 char mp[1007][1007];
 9 int vis[1007][1007], t[1007][1007];
10
11 struct node{
12     int x, y;
13     int step;
14 }nw, nxt;
15
16 int dx[4] = {1, -1, 0, 0}, dy[4] = {0, 0, 1, -1};
17
18
19 void bfs1() {
20     queue<node> q;
21     for(int i = 0 ; i< r; i++) {
22         for(int j = 0; j < c; j++) {
23             if(mp[i][j] == 'F') {
24                 nw.x = i, nw.y = j;
25                 t[i][j] = 0;
26                 q.push(nw);
27             }
28         }
29     }
30     while(!q.empty()) {
31         nw = q.front(), q.pop();
32         for(int i = 0; i < 4; i++) {
33             nxt.x = nw.x + dx[i], nxt.y = nw.y + dy[i];
34             if(nxt.x >= 0 && nxt.x < r && nxt.y >= 0 && nxt.y < c && mp[nxt.x][nxt.y] != '#' && t[nxt.x][nxt.y] > t[nw.x][nw.y] + 1) {
35                 t[nxt.x][nxt.y] = t[nw.x][nw.y] + 1;
36                 q.push(nxt);
37             }
38         }
39     }
40 }
41
42 void bfs2(int x, int y) {
43     nw.x = x, nw.y = y, nw.step = 0;
44     vis[x][y] = 1;
45     queue<node> q;
46     q.push(nw);
47     while(!q.empty()) {
48         nw = q.front(), q.pop();
49         if(nw.x ==0 || nw.x == r - 1 || nw.y == 0 || nw.y == c - 1) {
50             ans = nw.step + 1;
51             return;
52         }
53         for(int i = 0; i < 4; i++) {
54             nxt.x = nw.x + dx[i], nxt.y = nw.y + dy[i];
55             if(nxt.x >= 0 && nxt.x < r && nxt.y >= 0 && nxt.y <c && mp[nxt.x][nxt.y] != '#' && nw.step + 1 < t[nxt.x][nxt.y] && vis[nxt.x][nxt.y] == 0) {
56                 vis[nxt.x][nxt.y] = 1;
57                 nxt.step = nw.step + 1;
58                 q.push(nxt);
59             }
60         }
61     }
62 }
63
64 int main() {
65     scanf("%d", &T);
66     while(T--) {
67         scanf("%d%d", &r, &c);
68         for(int i = 0; i < r; i++) {
69             scanf("%s", mp[i]);
70             for(int j = 0; j < c; j++) {
71                 if(mp[i][j] == 'J') {
72                     sx = i, sy = j;
73                 }
74             }
75         }
76         memset(vis, 0, sizeof(vis));
77         memset(t, inf, sizeof(t));
78         ans = inf;
79         bfs1();
80         bfs2(sx, sy);
81         if(ans >= inf) printf("IMPOSSIBLE\n");
82         else printf("%d\n", ans);
83     }
84     return 0;
85 }