这个问题使用优先级排序的队列思想方式怎么实现的，要求C语言解释

Problem Description
Farmer John's N cows (1 <= N <= 100,000) are lined up in a row.Each cow is labeled with a number in the range 1...K (1 <= K <=10,000) identifying her breed. For example, a line of 14 cows might have these breeds:

1 5 3 2 5 1 3 4 4 2 5 1 2 3

Farmer John's acute mathematical mind notices all sorts of properties of number sequences like that above. For instance, he notices that the sequence 3 4 1 3 is a subsequence (not necessarily contiguous) of the sequence of breed IDs above. FJ is curious what is the length of the shortest possible sequence he can construct out of numbers in the range 1..K that is NOT a subsequence of the breed IDs of his cows. Help him solve this problem.

Input

• Line 1: Two integers, N and K

• Lines 2..N+1: Each line contains a single integer that is the breed ID of a cow. Line 2 describes cow 1; line 3 describes cow 2; and so on.

Output

• Line 1: The length of the shortest sequence that is not a subsequence of the input

Sample Input
14 5
1
5
3
2
5
1
3
4
4
2
5
1
2
3

Sample Output
3