题目描述

The long road through Farmer John's farm has $N$ crosswalks across it, conveniently numbered $1 \"ldots N$ ($1 \"leq N \"leq 100,000$). To allow cows to cross at these crosswalks, FJ installs electric crossing signals, which light up with a green cow icon when it is ok for the cow to cross, and red otherwise. Unfortunately, a large electrical storm has damaged some of his signals. Given a list of the damaged signals, please compute the minimum number of signals that FJ needs to repair in order for there to exist some contiguous block of at least $K$ working signals.
共有N个信号灯，编号为1~N，有B个信号灯损坏，给你它们的编号。
问，最少修好几个信号灯，可以有K个编号连续的信号灯。

输入格式：

The first line of input contains $N$, $K$, and $B$ ($1 \"leq B, K \"leq N$). The next $B$ lines each describe the ID number of a broken signal

输出格式：

Please compute the minimum number of signals that need to be repaired in order for there to be a contiguous block of $K$ working signals somewhere along the road.

输入样例#1：

10 6 5
2
10
1
5
9

输出样例#1：

1