hard for me :(

Im having a difficulty in the instruction
{2824, 1774, -1490, -9084, -9696, 23094} => 1
how is that happen?

you say {1,100,50,-51,1,1} => 1
because {1} = {50,-51,1,1} => 1

AND

{1,2,3,4,3,2,1} => 3
because {1,2,3} = {3,2,1} => 3

So why {1,2,3,4,5,6} => -1?
{1,2,3} = {6} => 1 right?