Update Offline_Del.mdx

Author: envyaims

content/6_Advanced/Offline_Del.mdx

@@ -26,7 +26,7 @@ $\mathcal{O}(N \log^2 N)$ runtime. You _must_ use merging by rank. An explanatio
 
 ### Implementation
 
-Adding on to usual DSU, we can  store the parent
+Adding on to the usual DSU, we can store the parent
 and sizes of nodes that are being merged before each merge. This allows us revert each node to their parents before the merge so that the rollback function can use the information to undo the merges.
 
 We can store each state of the DSU using an integer, captured by the snapshot function which returns the number of old merges that has not been rolled back. It's similar taking a picture of something, and years later going back into your photo album and scrolling up until you find this picture.