function Ras()
{
var dvr;


if (document.forms[0].td.value==0){window.alert(" Ââåäèòå âûñîòó ñåòêè ");  return; }
if (document.forms[0].td2.value==0){window.alert(" Ââåäèòå øèðèíó ñåòêè ");  return; }
document.forms[0].res.value=1*document.forms[0].s.value*document.forms[0].td.value*document.forms[0].td2.value;}