how do i solve #3

This is in Java language

sEmpty to construct pseudocode operations that do each of the following: a se num to the second element from the top of the stack, leaving the stack with its top three elements. 20 b) Set num to the second element from the top of the stack, leaving the stack unchanged. Focus on Data Structures Page 127 c) Given an integer n, set num to the nth element from the top of the stack, leaving the stack without its top n elements. d) Given an integer n, set num to the nth element from the top of the stack, leaving the stack unchanged. e) Set num to the bottom element of the stack, leaving the stack empty. f) Set num to the bottom element of the stack, leaving the stack unchanged. 9) Set num to the nth element from the bottom of the stack leaving the stack unchanged