You are given a sequence of positive integers of length N, a = (a_1, a_2, ..., a_N).
Your objective is to remove some of the elements in a so that a will be a good sequence.
Here, an sequence b is a good sequence when the following condition holds true:
- For each element x in b, the value x occurs exactly x times in b.
For example, (3, 3, 3), (4, 2, 4, 1, 4, 2, 4) and () (an empty sequence) are good sequences, while (3, 3, 3, 3) and (2, 4, 1, 4, 2) are not.
Find the minimum number of elements that needs to be removed so that a will be a good sequence.

-----Constraints-----
- $1 \leq N \leq 10^5$
- a_i is an integer.
- $1 \leq a_i \leq 10^9$

-----Input-----
Input is given from Standard Input in the following format:
N
a_1 a_2 ... a_N

-----Output-----
Print the minimum number of elements that needs to be removed so that a will be a good sequence.

-----Sample Input-----
4
3 3 3 3

-----Sample Output-----
1

We can, for example, remove one occurrence of 3. Then, (3, 3, 3) is a good sequence.

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