text: what r these? 1-z 2-z* 3-n 4- [-z] 5- [+z]                          z- set of all integers - {...-3,-2,-1,0,1,2,3,...} n- set of all natural numbers - {1,2,3,4,5,6,....} -z - negative integers {-1,-2,-3,-4,-5,-6,.........} +z- positive integers (the same as natural numbers {1,2,3,4....}