type vector=array[1..1000000] of longint;
var f:text;
    a:vector;
    n:longint;
    s:int64;
procedure element;
var i,j:longint;
begin
for i:=2 to n do a[i]:=i-1;
for i:=1 to n div 2 do begin
    j:=2*i;
    while j<=n do begin
          a[j]:=a[j]-a[i];
          j:=j+i;
          end;
    end;
for i:=2 to n do
    s:=s+a[i];
s:=s*2+1;
end;
begin
assign(f,'fractii.in');
reset(f);
read(f,n);
close(f);
element;
assign(f,'fractii.out');
rewrite(f);
write(f,s);
close(f);
end.