type vec=array[1..10000] of byte;
var i,j,k,nr,n:longint;
    p:vec;
begin
assign(input,'fractii.in');
assign(output,'fractii.out');
reset(input);
rewrite(output);

read(n);

k:=n-1; {numarul fractiilor reductibile de forma 2/2 3/3...}
for i:=2 to (n div 2) do
      begin
      if p[i]=0 then
                begin
                j:=i*2;
                while j<=n do
                      begin
                      k:=k+2;  {cu doua numere care se divid putem forma}
                      p[j]:=1; {doua fractii reductibile... a/b si b/a}
                      j:=j*i;
                      end;
                end;
      end;
nr:=n*n-k; {din numarul fractiilor existente scadem fractiile reductibile}
write(nr);

close(input);
close(output);

end.