public class TestDigraph {
    public static void main(String[] args) {

	Digraph g1 = new Digraph();
	g1.addVertex("A");
	g1.addVertex("B");
	g1.addVertex("C");
	g1.addVertex("D");
	g1.addEdge("A","B");
	g1.addEdge("B","C");
	g1.addEdge("C","D");
	System.out.println(g1.isCyclic());

	Digraph g2 = new Digraph();
	g2.addVertex("A");
	g2.addVertex("B");
	g2.addVertex("C");
	g2.addVertex("D");
	g2.addEdge("A","B");
	g2.addEdge("B","C");
	g2.addEdge("C","D");
	g2.addEdge("D","A");
	System.out.println(g2.isCyclic());

	
    }



}