def all_paths_sum_k(root, k):
    """
    Args:
     root(BinaryTreeNode_int32)
     k(int32)
    Returns:
     list_list_int32
    """
    # Write your code here.
    if root is None:
        return []
    result = []
    def dfs(node, target, slate):
        ## base case - leaf node
        if node.right is None and node.left is None:
            if target == node.value:
                slate.append(node.value)
                result.append(slate[:])
                slate.pop()

        ## recursive case
        slate.append(node.value)
        if node.left is not None:
            dfs(node.left, target-node.value, slate)
        if node.right is not None:
            dfs(node.right, target-node.value, slate)
        slate.pop()

    dfs(root, k, [])
    paths = [[-1]] if len(result) == 0 else result
    return paths