var active = 1;

function next(){
	if( $( 'screen.img:animated' ).length != 0 ){
		return false;
	}
	++active;
	$( '.screen img:visible' ).fadeOut( '500' );
	$( '#image' + active ).fadeIn( '500' );
	$( '#previous' ).show();
	if( active == 5 ){
		$( '#next' ).hide();
	}
};

function previous(){
	if( $( 'screen.img:animated' ).length != 0 ){
		return false;
	}
	--active;
	$( '.screen img:visible' ).fadeOut( '500' );
	$( '#image' + active ).fadeIn( '500' );
	$( '#next' ).show();
	if( active == 1 ){
		$( '#previous' ).hide();
	}
};

$( function(){
	$( '#previous' ).click( previous );
	$( '#next' ).click( next );
});