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.