# Topic : Greedy _ 2+1 세일
#
# Python 3 : 시간초과
# PyPy 3 : 208ms

N = int(input())

greek = [ int(input()) for _ in range(N) ]

greek.sort(reverse=True)

for i in range(2,N,3):
  greek[i] = 0

print(sum(greek))