#include<bits/stdc++.h>
using namespace std;

int d[100002];

int main(){
	int n,k,b,c,minn=100002;
	scanf("%d %d %d",&n,&k,&b);
	while(b--){
		scanf("%d",&c);
		d[c]=1;
		d[c]+=d[c-1];
	}
	for(int i=k;i<=n;i++){
		minn=min(minn,d[i]-d[i-k]);
	} 
	printf("%d",minn);
	return 0;
}

感激不尽