Please can someone tell me how to do a basic scoring system to go into this code.

```
import random
print 'Welcome to Rock, paper, scissors!'
firstto=raw_input('How many points do you want to play before it ends? ')

playerscore=+0
compscore=+0

while True:
    choice = raw_input ('Press R for rock, press P for paper or press S for scissors, CAPITALS!!! ')

    opponent = random.choice(['rock', 'paper' ,'scissors' ])

    print 'Computer has chosen', opponent

    if choice == 'R' and opponent == "rock":
        print 'Tie'
        playerscore = playerscore+0
        compscore = compscore+0

    elif choice == 'P' and opponent == "paper":
        print 'Tie'
        playerscore = playerscore+0
        compscore = compscore+0

    elif choice == 'S' and opponent == "scissors":
        print 'Tie'
        playerscore = playerscore+0
        compscore = compscore+0

    elif choice == 'R' and opponent == "paper":
        print 'CPU Wins'
        playerscore = playerscore+0
        compscore = compscore+1

    elif choice == 'P' and opponent == "scissors":
        print 'CPU Wins'
        playerscore = playerscore+0
        compscore = compscore+1

    elif choice == 'S' and opponent == "rock":
        print 'CPU Wins'
        playerscore = playerscore+0
        compscore = compscore+1

    elif choice == 'P' and opponent == "rock":
            print 'You Win'
            playerscore = playerscore+1 
            compscore = compscore+0

    elif choice == 'S' and opponent == "paper":
            print 'You Win'
            playerscore = playerscore+1
            compscore = compscore+0

    elif choice == 'R' and opponent == "scissors":
            print 'You Win'
            playerscore = playerscore+1
            compscore = compscore+0

    print 'Player score is',playerscore
    print 'Computer score is',compscore

    if playerscore == firstto:
        'You won the game :)'
        exit()
    elif compscore == firstto:
        'You lost the game :('
        exit()

```