program PrimePalindromes;

uses crt;

var
  infile,outfile:text;
  x, y:longint;
  L, U, start, numpp: longint;
  prime: array[2..1000000] of boolean;

function ispalin(num:longint): boolean;
  var
    nums:string;
    x, l:integer;
    palin:boolean;
  begin
    str(num,nums);
    palin:=true;
    l:=length(nums);
    case l of
      1: palin:=true;
      2: begin
           if nums[1]<>nums[2] then
             palin:=false;
         end;
      else
         begin
           for x:= 1 to l div 2 do
             if nums[x] <> nums[l-x+1] then
               palin:=false;
         end;
    end;
    ispalin:=palin;
  end;

begin
  for x:=2 to 1000000 do
    prime[x]:=true;
  start:=2;
  while start <= 500000 do
    begin
      for x:=2 to 1000000 div start do
        prime[start*x]:=false;
      repeat
        inc(start);
      until prime[start];
    end;
  assign(infile,'DATA51.txt');
  reset(infile);
  assign(outfile,'OUT51.txt');
  rewrite(outfile);
  for x:=1 to 5 do
    begin
      readln(infile,L,U);
      numpp:=0;
      for y:= L to U do
        begin
          if ispalin(y) then
            begin
              if prime[y] then
                inc(numpp);
            end;
        end;
      writeln(outfile,numpp);
    end;
  close(infile);
  close(outfile);
end.