import java.io.*;
import java.util.*;
import java.awt.geom.*;

/**
 * Solution to Excellence
 * 
 * @author vanb
 */
public class excellence_vanb
{
    public Scanner sc;
    public PrintStream ps;
        
    /**
     * Driver.
     * @throws Exception
     */
    public void doit() throws Exception
    {
        sc = new Scanner( System.in );
        ps = System.out;;

        int n = sc.nextInt();
        int students[] = new int[n];
        for( int i=0; i<n; i++ )
        {
            students[i] = sc.nextInt();
        }

        // All we need to do is match up the worst student with the best, 
        // second worst with second best, and so on.
        // The smallest of those pairwise sums is our answer.
        // Here's a proof: Take 4 students (2 is trivial, 3 can't happen since we're guaranteed 
        // an even number of kids). WOLOG, assume all 4 are unique.
        //
        // Let x be the best. The second best is x-a, a>0.
        // Let y be the worst. The second worst is y+b, b>0.
        // Here's the order:
        // x
        // x-a
        // y+b
        // y
        // our answer is min( x+y, (x-a)+(y+b) ).
        //
        // Suppose we paired them differently: x with y+b, y with x-a
        // Then our answer would be min( x+y+b, x+y-a ) = x+y-a (since a>0, b>0, so b>-a)
        // but since a>0 and b>0, x+y-a has to be worse than x+y, 
        // and it also has to be worse than x+y-a+b. 
        //
        // Any ordering you can come up with can be obtained from the claimed optimal solution
        // by a series of such swaps, each one making the answer worse. So, the claimed optimal
        // solution is, indeed, optimal.
        Arrays.sort( students );
        
        int minimum = Integer.MAX_VALUE;
        for( int i=0; i<n/2; i++ )
        {
            int sum = students[i] + students[n-i-1];
            if( sum<minimum ) minimum = sum;
        }
        
        System.out.println( minimum );
    }
    
    /**
     * @param args
     */
    public static void main( String[] args ) throws Exception
    {
        new excellence_vanb().doit();        
    }   
}