program test_number;

{$APPTYPE CONSOLE}

uses
  SysUtils,math;

var a,b:array[1..1000000] of integer;
t,i,n,k,j:integer;
begin
for i:=1 to 10 do
begin
{assign(output, 'circle'+inttostr(i)+'.in');
rewrite(output);
randomize;
if i<=2 then n:=random(10)+1 else
if i<=4 then n:=random(90)+10 else
if i<=6 then n:=random(9000)+1000 else
if i<=8 then n:=random(90000)+10000 else
if i<10 then n:=random(900000)+100000 ELSE
if i=10 then n:=1000000;
writeln(n);

for j:=1 to n-1 do
write(random(n)+1, ' ');
writeln(random(n)+1);
close(output);

    }
assign(input, 'circle'+inttostr(i)+'.in');
reset(input);
assign(output, 'circle'+inttostr(i)+'.out');
rewrite(output);

for j:=1 to 1000 do b[j]:=0;
readln(n);
for j:=1 to n do begin
read(t);b[t]:=1;
end;
k:=0;
for j:=1 to n do begin
//write(b[j],' ');
k:=k+b[j];
end;
//writeln(k);
k:=0;
for j:=1 to n do
begin
if ((b[j]>0)and(j mod 2=1))then k:=k+1;
if ((b[j]>0) and  (j mod 2=0)and (b[j div 2]=0))
then begin k:=k+1;end;
if ((b[j]>0) and  (j mod 2=0)and (b[j div 2]>0))
then b[j]:=0;

end;
writeln(k);
close(input);
close(output);
end;

end.