The problem states:
 "[output]The graves shall be sorted by the distance that Lara will have to run from this grave to the cemetry entrance."
But in the sample output:
####
5 2
5 1
4 1
3 1
2 1
2 2
2 3
3 3
4 3
####
Clearly (2,1) is the nearest grave to entrace (1,1), but it appears in the middle !
Another thing is: (4,3) has not been digged by the time Lara is detected. So Lara shouldn't have time to be able to be (4,3). But (4,3) is in the sample output.
I think before Lara is detected, she does a snake shaped traversal( (1,1)->(1,2)->(1,3)->(1,4)->(2,4)->... ), am I right?
And what is the right interpretation of this problem, please ?

Lara runs through the underground passage she dugged before.
And "graves shall be sorted by the distance" through this passage. As you can see output is a part of passage.

Lara is detected only then she stoled treasure.

Lara does a right spiral traversal.

Thanks Pavel, now I got ac. This problem is pretty easy after one figures out what it means