var f,g:text;
    a:array[1..100]of integer;
    nr,n,j,i:integer;

BEGIN
assign(f,'fractii.in');reset(f);
assign(g,'fractii.out');rewrite(g);
read(f,n);
close(f);

nr:=0;

for i:=1 to n do
a[i]:=i;

for i:=2 to n do
if a[i]=i then begin
j:=i;
while j<=n do begin
j:=j+i;
a[j]:=a[j] div (i*(i-1));
end;
end;


for i:=2 to n do
nr:=nr+a[i];

write(g,2*nr +1);

close(g);
end.