The A&B&C three problems are not hard at all, but it still takes me 47 minutes to solve them.
The D&E&F three problems are really hard to solve.
It seems that from ranking 50 to ranking 900 are all contestants who solves three problems, it just depends on how fast they do it.
There are also past ARC's that contains easy A&B&C, but extremely hard D&E&F which, for me, are impossible to do.
