The "end of the list of positive integers"?Whereis the "end"? The set of positive integers is infinite. A list of them does NOT have an "end".

Every integer is either 0, positive or negative. You can map them into the positive integers by:

f(0)= 1

f(n)= 2n+ 1 if n is positive

f(n)= -2n if n is negative.

That is, 0 is mapped to 1, the positive integers are mapped to the odd positive integers in order and the negative integers are mapped to the even positive integers.