N, M, X = gets.split(" ").map{|s| s.to_i}

A = Hash.new {|hash, key| hash[key] = Array.new}

N.times {
	a, b = gets.split(" ").map{|s| s.to_i}
	A[b] << a
}

k = gets.to_i
c = gets.split(" ").map{|s| s.to_i}

list = []
A.values.each {|v|
	v.sort!.reverse!
	v[0] += X
	list += v
}

list.sort!.reverse!

cnt = [0]

0.upto(c.max-1) {|i|
	cnt << cnt[-1] + list[i]
}

total = 0
c.each {|i|
	total += cnt[i]
}
puts total