How much reputation does a steam user have? Introduction

For those not familiar with steam - or at least this particular aspect:

Often on peoples' profiles, people leave comments saying either "+rep _____" or "-rep _____". These are an unofficial means of showing whether you think someone in the community has a good or a bad reputation, for a number of reasons. Such comments look like:


  +rep a good player
  
  +rep helpful
  
  -rep hacker
  
  -rep scammer




Task

The program must take input through any consensual way. The input consists of a string with optional newlines (\n). At the very start of each line, '+rep ' or '-rep ' might be present. The rest of the line can be discarded. If the line doesn't start with '+rep ' or '-rep ' (note the trailing space), the line should be ignored.

The program then must keep a total reputation score. Starting at 0, this score should be incremented on every line that starts with '+rep ' and decremented on every line that starts with '-rep '.

This result should be output in any agreed-upon way.


Test cases

Input:
+rep fast trade
+rep nice person
-rep too good

Output: 1

Input:
-rep hacker
-rep scammer
-rep was mean

Output: -3

Input:
first
i don't like him
+rep good at cs go

Output: 1

Input (note the lack of a trailing space on the third line):    
+rep +rep
hi +rep
-rep

Output: 1

Input:
+ rep

Output: 0

Input:
+rep like
-thing

Output: 1




Bonus

I don't even know if it's possible, but bonus points if you can somehow get these comments from Steam.
Python 3, 73 bytes

I'm sure this answer is garbage and will be beaten soon, but there's no other python answers yet

lambda x:sum(["- +".index(i[0])-1for i in x.split('\n')if i[1:4]=="rep"])


Use like this:

f = lambda x:sum(["- +".index(i[0])-1for i in x.split('\n')if i[1:4]=="rep"])
print(f("PUT INPUT HERE"))




Fetching from steam

Here's some sample code which fetches the first 100 comments from KennyS' profile and calculates his rep.

import requests
from bs4 import BeautifulSoup

# Kenny's profile as Steam ID 64
# You can adjust this to whatever numbers you want
STEAM_PROFILE_URL = "76561198024905796"
payload =  {"start" : 0, "count" : 100}
r = requests.post("http://steamcommunity.com/comment/Profile/render/{}/-1/".format(STEAM_PROFILE_URL), payload)

# Comments are html inside a json object
soup = BeautifulSoup(r.json()["comments_html"], "html.parser")

# Get raw text for every comment.
# The " ".join() strips out the newlines and tabs which are part of html
comments = [" ".join(s.text.split()) for s in soup.find_all("div", {"class" : "commentthread_comment_text"})]

calculateRep = lambda x:sum(["- +".index(i[0])-1for i in x.split('\n')if i[1:4]=="rep"])

print(calculateRep("\n".join(comments)))