Graph in C++

#include <list>

class Graph {
   public:
       Graph(int vertices);
       ~Graph();
       void addEdge(int from, int to);
       std::list<int> getEdges(int vertex);

   private:
       int V;
       std::list<int> * adj;
};

Graph::Graph(int vertices) {
   this->V = vertices;
   adj = new std::list<int>[vertices];
   for(int i = 0; i < vertices; ++i) {
       adj[i] = std::list<int>();
   }
}

Graph::~Graph() {
   delete[] this->adj;
}

void Graph::addEdge(int from, int to) {
   adj[from].push_front(to);
   // adj[to].push_front(from);
}

std::list<int> Graph::getEdges(int vertex) {
   if(vertex > this->V) return std::list<int>();
   return this->adj[vertex];
}