#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
#include <map>


/*
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::::::::::'' ,;!!!;,`::::::::::' .-`.,,,zcccc,,cccd$$"",;> `::::::::::::::
:::::::::' ;!!!!!!!!; ``:::::' ;' ,c$$$$$$$$$$$CC<<"  ````_ ::::::::::::::
:::::::' ;!!!!!!!!!!!!!;   ' ;! z$$$$$$$$$$$$$$$$$$$$$$??". ::::::::::::::
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:::::: ,!!!!!!!!!!!'`,;! .<! ,$$$$$$$$$$$$$$$$hc,,,..- !!!! `:::::::::::::
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::: ;><!!!!!!!!! ,<!!!!!!!',c,  "??.< . "??h. -;;;;!!!!!!!' ::::::::::::::
::: !!!!!!!!!!' ;!!!!!!!!' d$$h.`$ccr,$h `;,."  `!!!!!!!!! :::::::::::::::
:::.`<!!!!!!!' !!!!!!!!!! dP"""?.`$$F`$$h.`!!!!!!!!!!!!!! .:::::::::::::::
::::. <!!!!!! !!!!!!!!!! ,$ .nn.' "$$ P"   <!!!!!!!!!!!' .::::::::::::::::
:::::. <!!!! ;!!!!!!!!!! $$ MMMMx  ?$  ,dx `!!!!!!!!!!' ::::::::::::::::::
```:::: `!!! !!!'!!!!!!  `$ MMMMMM, $r MMMr !!!!!!!!' .:::::::::::::::::::
`!!;,.`' ``' ``,;!!!!' ch." 4MMMMMM "$ 4MMM `!!!!!' ..::::::::::::::::::::
!!!!!'````'``<!!!'`.z$$$$.  MMMMMMb $h MMM `!!'' .:::::::::::::::::::::::
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dM""..""?$$$$$$$$$$$$$$$$$$c  "MM"   $$>`   ,c  `:::::::::::::::::::::::::
MMn.`"?hc,d$$$$$$$$$$$$$$$$$$. `P    $P'   -??P== `:::::::::::::::::::::::
MMMMMnx`"?$$$$$$$$$$$P".,.`"??$ccccc$.z$$$$.  `' .:::::::::::::::::'    ''
MMMMMM,' .?$$$$$$$$$$ d$$$    d$$$$$$$$$$$$$h..``::::::::::::::::'
MMMMMMMn `?$$$$$$$$$$,.?$$h. =."?$$$$$$$$$$$$$$hc,.``'::::::::::'
MMMMMMMM ;, `"??$$$$$$h  ?$$h. -m,``""??$$$$$$$$$$$$$c,.``````'
MMMMMMM> !!! ?cc,.,d$$$$h.`"?$hc   `P  .`"?$$$$$$$$$$$$$$$$$$$          .:
MMMMMMM ,!!'. $$$$$$$$$??=== `"""=c, " P  n. "$$$$$$$$$$$$$$$$c_    ,.::::
MMMMMMP !!! Mr<$$$$"".,c,;M ;<!! ..""=_ ' 4 .br .`""??$$$$$$$$??"".:::::::
MMMMMM';!!',M>'$$$$$$$$$>4M `!!! 4MMbn.`"=cc," -'P",c=.,.`.. .=  :::::::::
MMMMM' !!! dMb $$$$$$$$P MM> !!! 4MMMMMMr :..`"-._""Pr4"'-P" .,.`:::::::::
MMMM' <!!!,MMM "$$$$$$P dMM>;!!! 4MMMMMMb :::::.. "-=cczyycc??" .:::::::::
MMMP <!!! dMMMb "?$$P" uMMM>;!!! 4MMMMMMMr`:::::::::.........:::::::::::::
MMP';!!! ;MMMMMMn,.".uMMMMM ;!!! MMMMMMMMM,`::::::::::::::::::::::::::::::
MM ;!!!! MMMMMMMMMMMMMMMMMM !!!! MMMMMMMMMb `:::::::::::::::::::::::::::::
M" !!!! uMMMMMMMMMMMMMMMMMP !!! ;MMMMMMMMMMx :::::::::::::::::::::::::::::
P.!!!! ,MMMMMMMMMMMMMMMMMM ,!!! MMMMMMMMMMMMx`::::::::::::::::::::::::::::
!!!!> MMMMMMMMMMMMMMMMMMP !!!',MMMMMMMMMMMMM `:::::::::::::::::::::::::::
*/


int main() {
	int n;

	std::cin >> n;

	std::vector<long long> v(3 * n);
	for (int i = 0; i < 3 * n; i++)
	{
		std::cin >> v[i];
	}

	std::sort(v.begin(), v.end());
	std::reverse(v.begin(), v.end());

	long long ans = 0;
	for (int i = 0; i < n; i++)
	{
		ans += v[i * 2 + 1];
	}

	std::cout << ans << std::endl;
	return 0;

}

Measured memory_bytes: 2560