Problem

A map is given, consisting of ~N \times N~ small squares. Each square can be either empty (denoted by a blank space) or contain an obstacle (denoted by the letter "~X~"). Tasos is located in an empty square (denoted by the letter "~T~") and Golfo is located in another (denoted by the letter "~G~").

Tasos wants to meet Golfo. Each time, he can move to one of the neighboring squares (up, down, left, and right). Moving left or right costs ~1~ unit, moving up costs ~2~ units, while moving down costs nothing.

Our goal is to find the minimum cost for Tasos to reach Golfo.

Input

The first line of the input will contain a natural number ~N~: the dimension of the map. The next ~N~ lines will contain the map. Each line will contain ~N~ characters, each of which will either be a blank space, or one of the letters "~X~", "~T~", or "~G~". There will be exactly one "~T~" and one "~G~". Also, consider that the characters on the borders of the map will always be "~X~".

Output

The output should consist of one line containing either a natural number (the minimum cost of Tasos' movement from his initial position to where Golfo is located) or the word "~IMPOSSIBLE~" (in uppercase letters), if Tasos cannot reach Golfo.

Constraints

~4 \le N \le 500~
Execution time limit: 1 sec.
Memory limit: 64 MB.

Examples of Input - Output

1st

STDIN (golfo.in)

10
XXXXXXXXXX
X        X
X T      X
XXXXXXXX X
X      X X
X  X     X
X  XXXXXXX
X       GX
X        X
XXXXXXXXXX

STDOUT (golfo.out)

20

2nd

STDIN (golfo.in)

8
XXXXXXXX
X T    X
XXXXXX X
X  X   X
X  XXXXX
X      X
X     GX
XXXXXXXX

STDOUT (golfo.out)

IMPOSSIBLE