uses crt;

var i,n,s:longint;

{-------------------------------}

function nt(x:longint):boolean;
var h:longint;
begin
   for h:=2 to trunc(sqrt(x)) do if (x mod h=0) then exit(false);
   exit(true);
 end;
{----------------------------------}

begin

clrscr;

readln(n);

s:=0;

for i:=1 to n do if (nt(i)) then s:=s+i;

write(s);

readln

end.

uses crt;
var n,i,s:longint;
{---Ham-nguyen-to---}
function nt(n:longint):boolean;
var i:longint;
begin
   i:=2;
   while n mod i<>0 do inc(i);
   if i=n then
      nt:=true
   else
      nt:=false;
end;
{---Chuong-trinh-chinh---}
begin
   clrscr;
   write('Nhap n: '); read(n);
   for i:=2 to n do
      if nt(i) then
         inc(s,i);
   writeln('Tong nguyen to: ',s);
   readln
end.