program ciur;
{$APPTYPE CONSOLE}
uses
  SysUtils;

var c,i,j,n,m:Longint;
    fin,fout:text;
    v:array [1..2000000] of byte;
begin
        assign(fin,'ciur.in'); reset(fin);
        assign(fout,'ciur.out'); rewrite(fout);
        readln(fin,n);
        for i:=1 to n do v[i]:=1; //v[n+1]:=1;
        for i:=2 to n do
        begin
                if v[i] = 1 then
                begin
                        inc(c);
                        j:=i;
                        While j < n do
                        begin
                                inc(j,i);
                                v[j]:=0;

                        end;
                end;
        end;

        writeln(fout,c);

        close(fin);
        close(fout);
end.