##### 2014 Mock CCC by Alex and Timothy

Alice's love for Bob is everlasting. Unfortunately, they are fated to be
apart in the current time. Alas, her burning love cannot be stopped by
such a small obstacle. To reach Bob, Alice has acquired a time machine
with settings, along with maps of the terrain
from each of those time periods. One of those periods is the present
day. Alice and Bob live in a rectangular world that's units tall by
units wide . In their world, places where they
may walk are denoted by `.`

, and obstacles (places where they may not
walk) are denoted by `X`

.

From Alice's perspective of time, it takes second to move in any of the four directions adjacent to her (up, down, left, or right). It also takes her second to travel to any one of the time periods supported by her time machine. Whenever she travels through time, she always lands exactly on the same location. Of course, she cannot travel to another time if her location in that time is occupied by an obstacle. Alice would like to know the shortest time (from her own perspective) that it takes to get from her location in present day to Bob's location in present day.

#### Input Specification

The first line of input contains the integers , , and , the
dimensions of the map and the number of time periods accessible by
Alice's time machine.

The following contains maps, each rows by columns. The first
of these maps describes the present day. In the present day map, `A`

indicates Alice's current position and `B`

indicates Bob's current
position. It is guaranteed that Alice cannot reach Bob from traversing
only the present day setting.

#### Output Specification

The shortest time that it takes for Alice to reach Bob, in seconds from
Alice's perspective. If this is not possible, output `-1`

.

#### Sample Input 1

```
3 3 2
AXX
.X.
XXB
XXX
...
XXX
```

#### Sample Output 1

`6`

#### Explanation for Sample Output 1

There are two time settings, depicted below:

```
(Present Day)
Setting 0: Setting 1:
AXX XXX
.X. ...
XXB XXX
```

The best path Alice can take is: to reach Bob.

#### Sample Input 2

```
2 5 3
BXXA.
XXX.X
.XXXX
..XXX
X...X
X.X.X
```

#### Sample Output 2

`8`

#### Explanation for Sample Output 2

The three time settings are:

```
(Present Day)
Setting 0: Setting 1: Setting 2:
BXXA. .XXXX X...X
XXX.X ..XXX X.X.X
```

The best path she can take is: , on top of Bob.

## Comments