var f,g:text;
i,j,k,n:longint;
function prim:boolean;
var min,d:longint;

begin
        if i<j then
                min:=i
        else
                min:=j;

        prim:=true;
        d:=2;
        while prim and (d<=min div 2) do
                begin
                  if (i mod d=0) and (j mod d=0) then
                        prim:=false;
                d:=d+1;
                end;
end;
function fractii:integer;
begin
        fractii:=0;
        while i<=n do
        begin
        for j:=2 to n do
          if ((i mod j<>0) and (j mod i<>0)) and prim=true  then
                fractii:=fractii+1;
          i:=i+1;
          end;
end;
begin
        assign(f,'fractii.in');
        reset(F);
        assign(g,'fractii.out');
        rewrite(g);
        read(f,n);
        i:=2;
        k:=fractii;
        k:=k+(2*n)-1;
        write(g,k);
        close(f);
        close(g);
end.