int ans=0;
int fun(struct TreeNode* node, int k)
    {
        int lk = fun(node.left, k),rk = fun(node.right, k);
        bool isleaf = (lk == -1 && lk == rk);
        if (lk == 0 || rk == 0 || (isleaf && k == 0))
            ans+=node->data;
        if (isleaf && k > 0)
            return k - 1;
        if (lk > 0 && lk < k)
            return lk - 1;
        if (rk > 0 && rk < k)
            return rk - 1;

        return -2;
    }

    int Kdistance(TreeNode* root,int k)
    {
        if(root==NULL) return -1;
        fun(root,k);
        return ans;
    }