//rozparsujej parametry
function getParamValue(varname)
{
  var url = window.location.href;
  var qparts = url.split("?");				//rozdeli url

  if (qparts[1] == null) return null;

  var query = qparts[1];							//zjisti parametry
  var vars = query.split("&");
  var value;
	var parts;

  for (n=0; n < vars.length; n++)
  {
    parts = vars[n].split("=");
    
    if (parts[0] == varname) { value = parts[1]; break; }			//nalezeno
  }
	if(n == vars.length) return null;
	  
  value = unescape(value);
  value.replace(/\+/g," "); 					//plus nahradi mezerou

  return value;
}

//spocita cislo stranky
function getPageNum(mastery1, mastery2)
{
	var mindex = new Array();
	var mstart = new Array();
	var num;
	var offset = 7;
	
	if(mastery1 < 1 || mastery1 > 9 || mastery2 < 0 || mastery2 > 9) return offset;
	
	mstart[2] = 7;
	mstart[4] = 16;
	mstart[6] = 24;
	mstart[7] = 31;
	mstart[8] = 37;
	mstart[1] = 42;
	mstart[5] = 46;
	mstart[3] = 49;
	mstart[9] = 51;
	
	mindex[2] = 8;
	mindex[4] = 7;
	mindex[6] = 6;
	mindex[7] = 5;
	mindex[8] = 4;
	mindex[1] = 3;
	mindex[5] = 2;
	mindex[3] = 1;
	mindex[9] = 0;
	
	if(mastery2 == 0) num = mstart[mastery1];
	else num = mstart[mastery1] + mindex[mastery2] + 1;
	
	return num;
}