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 $a_i$ 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? \InputFile The first line contains one integer $n~(1 \le n \le 2 \cdot 10^5)$ --- the number of contests. The second line contains $n$ integers $a_1, a_2, ..., a_n~(1 \le a_i \le 2 \cdot 10^5)$ --- the number of problems in the $i$-th contest. \OutputFile Print one integer --- the maximum number of days Huseyn can train if he chooses the contests optimally.