error: invalid type argument of '->' (have 'int')|

I am getting the following error while creating a function for creating a graph using adjaceny LIST representation:

error: invalid type argument of '->' (have 'int')

I have marked the line (in comments) where I am getting this error as //error. Below is the code:

typedef struct GRAPH
{
    int V;
    int E;
    int *adj; //head pointer to the Linked List
} graph;

typedef struct NODE //Node of the Linked List
{
    int vertexNumber;
    struct NODE *next;
} node;

graph *adjListOfGraph()
{
    int i,x,y;
    node *temp;
    graph *g;
    g = (node *)malloc(sizeof(graph));
    if(!g)
    {
        printf("Memory Error in creating the graph");
        return;
    }
    scanf("Number of Vertex: %d, Number of Edges: %d", &g->V,&g->E);
    g->adj=(node *)malloc(g->V *sizeof(node));
    for(i=0;i<g->V;i++)
    {
        g->adj[i] = (node *)malloc(sizeof(node));
        g->adj[i]->vertexNumber = i;    //error
        g->adj[i]->next = g->adj[i];    //error
    }
    for(i=0;i<g->E;i++)
    { 
        scanf("Reading edges: %d %d", &g->V,&g->E);
        temp = (node *)malloc(sizeof(node));
        temp->vertexNumber = y;
        temp->next = g->adj[x];
        g->adj[x]->next = temp;   //error
        temp = (node *)malloc(sizeof(node));
        temp->vertexNumber =y;
        temp->next = g->adj[y];
        g->adj[y]->next = temp;   //error
    }
    return g;
}

Please have a look at lines commented as error. I have searched a lot and also tried replacing -> by . but useless.