n = int(input())
products = []
res = 0
for i in range(n):
p = int(input())
products.append(p)
# ๋ด๋ฆผ์ฐจ์์ผ๋ก ์ ๋ ฌ
products.sort(reverse=True)
for i in range(len(products)):
# ์ฐจ๋ก๋ก ์ธ๊ฐ์ฉ ๋ฌถ์์ ๋ ๋ฌด๋ฃ๋ก ์ง๋ถํ๋ ์๋ ์ ์ธํ๊ณ ๊ณ์ฐ
if i % 3 != 2:
res += products[i]
print(res)