program fractii;
var f,g:text;
    d,p,x,i,n:longint;
    a:array[1..1000000]of longint;
begin
assign(f,'fractii.in');reset(f);
assign(g,'fractii.out');rewrite(g);
readln(f,n);
x:=0;
for i:=2 to n do
    begin
    d:=2;
    while i mod d>0 do d:=d+1;
    while i mod d>0 do p:=p+1;
    x:=x+(a[i div (d*p)]*(1-(1 div d))*(d*p))
    end;
writeln(g,x);
close(f);
close(g);
end.