{
    Problema fractii
}

Program fractii;

Type vector = array[0..1000000] of Longint;

Var n, i, j, l, k, aux : Longint;
    c, c2 : vector;
    nr : int64;
    cod : boolean;

Begin
    Assign( input, 'fractii.in' );
    Reset( input );
        Readln( n );
    Close( input );

    nr := n shl 1;
    nr := nr-1;

    For i := 2 to n do
        if c[i] = 0 then
            Begin
                aux := i;
                j := aux;
                While j <= n do
                    Begin
                        j := j+aux;
                        c[j] := 1;
                    End;
            End;

    k := 0;
    For i := 2 to n do
        if c[i] = 0 then
            Begin
                k := k+1;
                c2[k] := i;
            End;
    k := k+1;
    c2[k] := n+1;
    c2[0] := 0;

    For i := 2 to n do
        Begin
        For j := 2 to i-1 do
            Begin
            l := 0;
            cod := true;
            While (c2[l] < j) do
                Begin
                    l := l+1;
                    if ( i mod c2[l] = 0 ) and ( j mod c2[l] = 0 )
                        then
                        Begin
                            cod := false;
                            break;
                        End;
                End;
            if cod then nr := nr+2;
            End;
        End;

    Assign( output, 'fractii.out' );
    Rewrite( output );
        Writeln( nr );
    Close( output );
End.