N,M,X = map(int,input().split()) from collections import defaultdict dic = defaultdict(list) # 種類:値 for _ in range(N): a,b = map(int,input().split()) dic[b].append(a) qs = [] for key, value in dic.items(): sval = sorted(value) sval[-1] += X qs += sval qs = sorted(qs) # 一方で、K人の管理 K = input() C = list(map(int,input().split())) S = [0] * (N + 1) # i問目まで解く人が何人いるか for c in C: S[c] += 1 for i in range(N - 1, -1, -1): S[i] += S[i + 1] ans = 0 for i in range(1, N + 1): if S[i] == 0: break ans += S[i] * qs.pop() print(ans)