#Code Written by : John Nixon
#Date: 14:08:2022  Time: 10:34:06
#Copyrights are applicable
import sys
import os
sys.setrecursionlimit(10000)
try:
    sys.stdin = open('./input.txt', 'r')
    sys.stdout = open('./output.txt', 'w')
except:
    pass

n = int(input())
arr = list(map(int,input().split()))
k  =int(input())
l = int(input())

for i in range(len(arr)):
    ppl = arr[i]
    while k > 0 and ppl > l:
        if ppl > l:
            ppl -= l
            k -= 1
    arr[i] = ppl

while k > 0:
    for i in range(len(arr)):
        ppl = arr[i]
        if ppl > 0:
            ppl = 0 if l > ppl else l - ppl
            k -= 1
            arr[i] = ppl
    else:
        break
ans = 0
for ppl in arr:
    ans += ppl


print(ans)