Pascal :

var a,b,c,n,i,j,s:integer;
     d:array[1..100] of integer;
 begin
 readln(n);
 for i:=1 to n do read(d[i]);
 for i:=1 to n-1 do
  for j:=i+1 to n do
   if d[i]<d[j] then begin
   s:=d[i];
   d[i]:=d[j];
   d[j]:=s;
   end;
   s:=0;
   for i:=1 to n do
   if i mod 2=0 then s:=s+d[i];
   writeln(s);
 end.