I am referring to this question: Derivative of cross entropy loss in word2vec
$CE(w, \hat{w}) = -\sum_{k}^{|V|} w_klog(\frac{\exp(w_k^T \hat{r})}{\sum_{j}^{|V|}exp(w_j^T\hat{r})})$
$= -\sum_{k}^{|V|} w_klog(\exp(w_k^T \hat{r}) + w_klog(\sum_{j}^{|V|}exp(w_j^T\hat{r}))$
How is the $ \sum_{k}^{|V|} $ disappearing in the second term? I think it has something to do with the one hot vector, but I cant figure it out?