Var a:array [1..1000000] of byte;
    f,g:text;
    n,p,i,j,k,l,s:longint;
Begin
assign (f,'fractii.in');
assign (g,'fractii.out');
reset (f);
rewrite (g);
Readln (f,n);
For i:=1 to n do
    begin
    for j:=2 to trunc(sqrt(i)) do
        if i mod j=0
        then
            begin
            k:=k+1;
            end;
    if k=0
    then
        begin
        a[i]:=1;
        end;
    end;
For i:=1 to n do
    for j:=1 to n do
    if (a[i]=1) or (a[j]=1)
    then
        s:=s+1;
Writeln (g,s-2);
close(f);
close(g);
end.