function rozdildatumu(prvni, druhe)
{
var day1, day2;
var month1, month2;
var year1, year2;

value1 = prvni;
value2 = druhe;

day1 = value1.substring (0, value1.indexOf ("."));
month1 = value1.substring (value1.indexOf (".")+1, value1.lastIndexOf ("."));
year1 = value1.substring (value1.lastIndexOf (".")+1, value1.length);

day2 = value2.substring (0, value2.indexOf ("."));
month2 = value2.substring (value2.indexOf (".")+1, value2.lastIndexOf ("."));
year2 = value2.substring (value2.lastIndexOf (".")+1, value2.length);

date1 = year1+"/"+month1+"/"+day1;
date2 = year2+"/"+month2+"/"+day2;

firstDate = Date.parse(date1)
secondDate= Date.parse(date2)

msPerDay = 24 * 60 * 60 * 1000
dbd = Math.round((secondDate.valueOf()-firstDate.valueOf())/ msPerDay) + 1;

return  dbd;

}





function kontrola_poslatvzkaz(form) {

 if (
     (form.jmeno.value == "") ||
     (form.email.value == "") 
     )
   {
    
      alert ("Vyplňte prosím všechny položky. Please fill all obligatory data.");
      return false;
   }
   

    
   
   if (form.email.value !="") {


      if (window.RegExp)
      {
        re = new RegExp("^[^.]+(\.[^.]+)*@([^.]+[.])+[a-z]{2,3}$");
        if (!re.test(form.email.value))
        {
          alert("Zadaný email není ve správném tvaru! Please write correctly your email address.");
          return false;
          form.email.focus();
        }
      }

    }
}