program prog2;

{$APPTYPE CONSOLE}

uses
  SysUtils,
  windows;

var a:array[1..100000000] of integer;
j,k,n,i:integer;
  time:int64;


begin
readln(n);
time:=gettickcount;
for i:=1 to n do a[i]:=i;
a[1]:=0;
i:=1;
while i<=n div 2 do begin
while a[i]=0 do i:=i+1;
//writeln(i);readln;
j:=i+a[i];
while j<=n do begin
a[j]:=0;
j:=j+a[i];
end;
i:=i+1;

//for k:=1 to n do write(a[k],' ');readln;
end;

for k:=1 to n do
if a[k]<>0 then ///write(a[k],' ');
writeln;
time:=gettickcount-time;
writeln(time/1000:0:5);

readln;
  { TODO -oUser -cConsole Main : Insert code here }
end.