Node *addToBST(int arr[], int start, int end)
{
    if(end < start) return NULL;
    int mid = (start + end)/2;
 
    Node *r = (Node*) malloc(sizeof(Node));
    r->data = arr[mid];
    r->left = addToBST(arr, start, mid-1);
    r->right = addToBST(arr, mid+1, end);
    return r;
}
 
Node *createMinimalBST(int arr[], int size)
{
    return addToBST(arr,0,size-1);
}