There are 3N participants in AtCoder Group Contest. The strength of the i-th participant is represented by an integer a_i. They will form N teams, each consisting of three participants. No participant may belong to multiple teams.

The strength of a team is defined as the second largest strength among its members. For example, a team of participants of strength 1, 5, 2 has a strength 2, and a team of three participants of strength 3, 2, 3 has a strength 3.

Find the maximum possible sum of the strengths of N teams.

Constraints

* 1 ≤ N ≤ 10^5
* 1 ≤ a_i ≤ 10^{9}
* a_i are integers.

Input

Input is given from Standard Input in the following format:


N
a_1 a_2 ... a_{3N}


Output

Print the answer.

Examples

Input

2
5 2 8 5 1 5


Output

10


Input

10
1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000


Output

10000000000
import java.io.*;
import java.math.*;
import java.util.*;


public class Main {

	public static void main(String[] args) throws Exception {
		new Main().solve();
	}
	void solve() throws Exception {
		FastScanner in = new FastScanner(System.in);

		int N = in.nextInt();
		long[] a = new long[N * 3];
		for (int i = 0; i < N * 3; i++) {
			a[i] = in.nextLong();
		}
		Arrays.sort(a);
		long sum = 0;
		for (int i = 0; i < N; i++) {
			sum += a[3 * N - 2 - i * 2];
			//System.out.println(i + "," + N + "," + (N - 2 - i * 2));
		}
		System.out.println(sum);


	}

	//
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	class FastScanner {

		private InputStream _stream;
		private byte[] _buf = new byte[1024];
		private int _curChar;
		private int _numChars;
		private StringBuilder _sb = new StringBuilder();

		FastScanner(InputStream stream) {
			this._stream = stream;
		}

		public int read() {
			if (_numChars == -1) throw new InputMismatchException();
			if (_curChar >= _numChars) {
				_curChar = 0;
				try {
					_numChars = _stream.read(_buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (_numChars <= 0) return -1;
			}
			return _buf[_curChar++];
		}

		public String next() {
			int c = read();
			while (isWhitespace(c)) {
				c = read();
			}
			_sb.setLength(0);
			do {
				_sb.appendCodePoint(c);
				c = read();
			} while (!isWhitespace(c));
			return _sb.toString();
		}

		public int nextInt() {
			return (int) nextLong();
		}
		public long nextLong() {
			int c = read();
			while (isWhitespace(c)) {
				c = read();
			}
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9') throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isWhitespace(c));
			return res * sgn;
		}

		public boolean isWhitespace(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
	}
}
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