set_discard_pop.py

"""

Problem Statement

.remove(x)
This operation removes element x from set. 
If element x is not in the set, it raises a KeyError.
.remove(x) operation returns None.

Example

>>> s = set([1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> s.remove(5)
>>> print s
set([1, 2, 3, 4, 6, 7, 8, 9])
>>> print s.remove(4)
None
>>> print s
set([1, 2, 3, 6, 7, 8, 9])
>>> s.remove(0)
KeyError: 0
.discard(x)
This operation also removes element x from set. 
But if element x is not in the set, it does not raises a KeyError.
.discard(x) operation returns None.

Example

>>> s = set([1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> s.discard(5)
>>> print s
set([1, 2, 3, 4, 6, 7, 8, 9])
>>> print s.discard(4)
None
>>> print s
set([1, 2, 3, 6, 7, 8, 9])
>>> s.discard(0)
>>> print s
set([1, 2, 3, 6, 7, 8, 9])
.pop()
This operation removes and return an arbitrary element from set. 
If there are no elements to remove, it raises a KeyError.

Example

>>> s = set([1])
>>> print s.pop()
1
>>> print s
set([])
>>> print s.pop()
KeyError: pop from an empty set
Task
You have a non-empty set s and you have to execute N commands given in N lines.

Commands will be pop, remove and discard.

Input Format

First line contains integer n, number of elements in set. 
Second line contains space separated elements of set s. All elements are non-negative integers, less than or equal to 9. 
Third line contains integer N, number of commands.
Next N lines contains pop, remove and discard commands.

Constraints

0<n<20 
0<N<20
Output Format

Print sum of elements of set 's' in output.

Sample Input

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

4
Explanation

On application of these 10 operations on set, we get set([4]). Hence, sum is 4.

Note : Convert elements of set s to integers while assigning. To ensure proper input of set we have added, first two lines of code to the editor.

"""

n = input()
s = set(map(int, raw_input().split())) 
a = input()

for i in xrange(a):
	k = []
	k = raw_input().split()
	if k[0] == 'pop':
		s.pop()
	elif k[0] == 'remove':
		s.remove(int(k[1]))
	elif k[0] == 'discard':
		s.discard(int(k[1]))
	else:
		print 'not a command'

print sum(s)