public boolean addEdge(int bottom,int top)
	{
		if(top < 0 || top >= vertexCount || bottom < 0 || bottom >= vertexCount) return true;
		if(adjacencyMatrix[top][bottom] == false) inDegrees[bottom]++;
		boolean rv = adjacencyMatrix[top][bottom];
		adjacencyMatrix[top][bottom] = true;
		return rv;
	}