program Project2;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  a:array[1..10000] of real ;
  i,n:integer;
  s1,s2,r :real;
begin
  readln(n);
  for i:=1 to 2*n do
  readln(a[i]);
  s1:=0;
  s2:=0;
  for i:=1 to n do
  s1:=a[i]+s1 ;
  for i:=n+1 to 2*n do
  s2:=a[i]+s2;
  r:=s1-s2;
  writeln('r= ',r:2:2);
  readln;
end.