function login(){
	var ok = 0;
	if(document.mainform.username.value.length<1){
		document.mainform.username.focus();
		alert('Inserire Username');
		return(false);
	}else{
		ok = 1;	
	}
		if(document.mainform.password.value.length<1){
		document.mainform.password.focus();
		alert('Inserire Password');
		return(false);
	}else{
		ok = ok+1;
	}

	if(ok==2){
		document.getElementById('access').style.display='block';
		setTimeout("location.href = 'main.php';",1500);

	}
}