ruby, 81 bytes

Result

WA

Duration

567ms

Code [DL]

require'matrix'
x=$<.map{|l|Vector[*l.split.map(&:to_i)]}
p -Matrix.rows(x).det/6

stdin

36 28 72
35 03 04
26 36 50
47 69 03

stdout

stderr

/usr/local/ruby-2.5.0/lib/ruby/2.5.0/matrix.rb:1105:in `determinant': Matrix dimension mismatch (ExceptionForMatrix::ErrDimensionMismatch)
	from /volume/CODE:3:in `<main>'

strace