Huseyn wants to train before another programming competition. During the first day of his training he should solve exactly 1 problem, during the second day — exactly 2 problems, during the third day — exactly 3 problems, and so on. During the k-th day he should solve k problems.
Huseyn has a list of n contests, the i-th contest consists of ai problems. During each day Huseyn has to choose exactly one of the contests he didn't solve yet and solve it. He solves exactly k problems from this contest. Other problems are discarded from it. If there are no contests consisting of at least k problems that Huseyn didn't solve yet during the k-th day, then Huseyn stops his training.
How many days Huseyn can train if he chooses the contests optimally?
The first line contains one integer n (1≤n≤2⋅105) — the number of contests.
The second line contains n integers a1,a2,...,an (1≤ai≤2⋅105) — the number of problems in the i-th contest.
Print one integer — the maximum number of days Huseyn can train if he chooses the contests optimally.