ctf_a_c.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
 
import os
import sys
 
class Hoge(object):
    
    def __init__(self):
        pass
 
    def func(self):
        '''
        insert your code
        '''
        n, m = map(int, raw_input().split())
        p = map(int, raw_input().split())
        s = map(int, raw_input().split())
 
        count = 0
        for i, e in enumerate(p):
            if i + 1 in s:                
                count += e
 
        print count
        
        
        return None
 
if __name__ == '__main__':
    h = Hoge()
    h.func()