https://www.hackerrank.com/challenges/py-set-discard-remove-pop/problem
Problem
.remove(x)
This operation removes element x from the set.
If element x does not exist, it raises a KeyError.
The .remove(x) operation returns None.
Task
You have a non-empty set s, and you have to execute N commands given in N lines.
The commands will be pop, remove and discard.
Input Format
The first line contains integer N, the number of elements in the set s.
The second line contains n space separated elements of set s. All of the elements are non-negative integers, less than or equal to 9.
The third line contains integer N, the number of commands.
The next N lines contains either pop, remove and/or discard commands followed by their associated value.
Output Format
Print the sum of the elements of set s on a single line.
Sample Input 0
9
1 2 3 4 5 6 7 8 9
10
pop
remove 9
discard 9
discard 8
remove 7
pop
discard 6
remove 5
pop
discard 5
Sample Output 0
4