Var a:array [1..1000000] of integer;
    f,g:text;
    n,i,suma,jk,coef,j:longint;
    ok:boolean;
Begin
assign (f,'fractii.in');
assign (g,'fractii.out');
reset(f);
rewrite (g);
readln (f,n);
jk:=0;
for i:=2 to n do
begin
     ok:=true;
     for j:=2 to trunc(sqrt(i)) do
     begin
     if i mod j=0
     then
         ok:=false;
     end;
     if ok
     then
         begin
         if jk < (n div i)-1
         then
             jk:=(n div i)-1;
         a[(n div i)-1]:=a[(n div i)-1]+1;
         end;
end;
coef:=0;
for i:=1 to jk do
begin
coef:=coef+i;
if a[i]<>0
then
    suma:=suma+(a[i]*coef);
end;
i:=n*n;
i:=i-(2*suma);
i:=i-n+1;
writeln (g,i);
close (f);
close (g);
End.