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

A = []

Max = Hash.new([-Float::INFINITY, -1])

N.times {
	a, b = gets.split(" ").map{|s| s.to_i}
	A << a
	Max[b] = [a, A.length-1] if a > Max[b][0]
}

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

Max.values.each {|a, i|
	A[i] += X
}

A.sort!

cnt = [0]

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

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