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var f:boolean;
    a,b,i,j:longint;
    s:string;
function check(n:longint):boolean;
var i,j,k:longint;
begin
  k:=round(sqrt(n));
  for i:=2 to k do
    if n mod i=0 then begin
      check:=false;
      exit;
    end;
  check:=true;
end;
begin
  readln(a,b);
  if b>9989899 then b:=9989899;
  for i:=a to b do begin
    str(i,s);
    f:=true;
    for j:=1 to length(s) div 2 do
      if s[j]<>s[length(s)-j+1] then begin
        f:=false;
        break;
      end;
    if f and check(i) then writeln(i);
  end;
end.