class Graph {
    int numberOfVertices;
    ArrayList<Integer>[] adjacencyList;
    public Graph(int numberOfVertices){
        this.numberOfVertices=numberOfVertices;
        adjacencyList=new ArrayList[numberOfVertices];
        for(int i=0;i<numberOfVertices;i++)
            adjacencyList[i]=new ArrayList<>();
    }

    public void addEdge(int x,int y){
        adjacencyList[x].add(y);
    }

    public ArrayList<Integer> getAdjacentVertices(int x){
        return adjacencyList[x];
    }

    public boolean hasEdge(int x,int y){
        return adjacencyList[x].contains(y);
    }

}