var f,g:text;
    j,i,n,cnt:longint;
    a:array[1..2000000] of byte;
BEGIN
assign(f,'ciur.in');reset(f);read(f,n);
assign(g,'ciur.out');rewrite(g);
writeln(n);
for i:=2 to n do
 begin
  if a[i]=0 then
   begin
   j:=i+i;
   while j<=n do
    begin
    a[j]:=1;
    j:=j+i;
    end;
   end;
 end;
 cnt:=0;
 for i:=2 to n do
 if a[i]=0 then  cnt:=cnt+1;
 write(g,cnt);
 close(f);close(g);
END.