interface AdjList {
    int beg();
    int nxt();
    boolean end();
}

class Edge {
    int v, w;
    double wt () { return 0.0; }
    Edge (int v, int w) { this.v = v; this.w = w; }
}

class GraphAdjList {
    private int Vcnt, Ecnt;
    private boolean digraph;
    private class Node {
	int v; Node next;
	Node (int x, Node t) { v = x; next = t; }
    }
    private Node adj[];

    GraphAdjList (int V, boolean flag) {
	Vcnt = V; digraph = flag;
    }

    int V () { return Vcnt; }
    int E () { return Ecnt; }

    boolean directed () { return digraph; }

    Edge edge (int v, int w) {
	return new Edge (v, w);
    }

    void insert (Edge e) {
	int v = e.v, w = e.w;
	adj[v] = new Node (w, adj[v]);
	if (!digraph) adj[w] = new Node (v, adj[w]);
	Ecnt = Ecnt + 1;
    }

    private class AdjLinkedList implements AdjList {
	private int v;
	private Node t;

	AdjLinkedList (int v) {
	    this.v = v; t = null;
	}

	public int beg() {
	    t = adj[v];
	    return (t == null)? -1 : t.v;
	}

	public int nxt() {
	    t = t.next;
	    return (t == null)? -1 : t.v;
	}

	public boolean end () {
	    return (t == null);
	}
    }

    AdjList getAdjList (int v) {
	return new AdjLinkedList(v);
    }

    static void randG(GraphAdjList G, int E) {
	int Vcnt = G.V();
	double p = (E + E)/ Vcnt / (Vcnt-1);
	    for (int i = 0; i < Vcnt; i++) {
		for (int j = i+1; j < Vcnt; j++) {
		    if (Math.random() < p) G.insert(new Edge(i, j));
		}
	    }
    }
}