i:.''0:"i/15"
l:(9999,'-1_');t:+l@+:;r:|'l@|:';b:|t@|:
f:*|*|{x&/i+/:(l;r;t;b)@\:x}/.[;0 0;:;0]@9999|
f@i
f@i:1+9!-1+,/,'/'(i+/)''5 5#+!5 5