function check_number(){
if((event.keyCode<48) || (event.keyCode>57)){
	event.returnValue = false;
	alert_warning_number();
} 
}
 function check_logout(){
  $('#overlay').show();	
  $('#preloader').html("Logout...").fadeIn();
  $.ajax({
		url:"logout.php",	   
		type: "POST",
		dataType: "json",
		success:function(data){
			unloading();
			setTimeout( "window.location.href ='?logout=true'", 1300 );
		  }		
	  });
	return false;			 
}