var intervals = [];
var current = [];

 $(document).ready(function(){
 	
	$(".slide_block").each(function(i) {
		var refer = this;
		$("img:first", $(this) ).show();
		current[ i ] = $("img:first", $(this) );
		intervals[ i ] = setInterval( function(){
			interval( refer, i );
		}, 4000 + Math.random()*4000 );
	});

});

function interval( papa, i ){
	var prev = current[i];
	if (  $( prev ).attr("src") == $( "img:last", $(papa) ).attr("src") ) {
		current[i] = $("img:first", $( papa ));
	} else {
		current[i] = $(current[i]).next();
	}
	$(current[i]).fadeIn( 1000 );
	$(prev).fadeOut( 1000 );
}