graph {
	layout=osage
		subgraph cluster_0 {
			label="composite cluster";
			subgraph cluster_1 {
			    label="the first cluster";
				C
				L
				U
				S
				T
				E
				R
			}
			subgraph cluster_2 {
			    label="the second\ncluster";
				a
				b
				c
				d
			}
			1
			2
		}
	3
	4
	5
}