import java.io.PrintStream;
import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;

/**
 * Solution to Star Guardians
 * 
 * @author vanb
 */
public class star_vanb
{
    /** Input. */
    private static Scanner sc;
    
    /** Output. */
    private static PrintStream ps;
    
    /**
     * Do it!
     */
    private void doit()
    {
        int n = sc.nextInt();
        Double a[] = new Double[n];
        for( int i=0; i<n; i++ ) a[i] = sc.nextDouble();
        Double s[] = new Double[n];
        for( int i=0; i<n; i++ ) s[i] = sc.nextDouble();
        
        Arrays.sort( s, Collections.reverseOrder() );
        
        double average = 0.0;
        double sum = 0.0;
        for( int i=0; i<n; i++ )
        {
            sum += s[i];
            double avg = (sum+a[i])/(i+1);
            if( avg>average ) average = avg;
        }
        
        ps.println( average );
    }
        
    /**
     * Main.
     * 
     * @param args unused
     * @throws Exception
     */
    public static void main( String[] args ) throws Exception
    {
        sc = new Scanner( System.in );
        ps = System.out;
        
        new star_vanb().doit();
    }

}