var i,j,k,l,m,n,o,p,q:longint;
begin
//  assign(input,'two.in');reset(input);
// assign(output,'two.out');rewrite(output);
  readln(m,n);
  p:=0;
  for i:=m to n do
    begin
      o:=i;
      while o<>0 do
        begin
          if o mod 10=2 then p:=p+1;
          o:=o div 10;
        end;
    end;
  writeln(p);
 // close(input);close(output);
end.


/**************************************************************
	Problem: 2292
	User: admin
	Language: Pascal
	Result: Wrong Answer
****************************************************************/