1 #include<cstdio>
2 #include<cstring>
3 #include<algorithm>
4 using namespace std;
5 int n,r,ans;
6 int a[1010];
7 int cmax(int x,int y){return x>y?x:y;}
8 int main()
9 {
10 scanf("%d%d",&r,&n);
11 while (n!=-1 && r!=-1)
12 {
13 memset(a,0,sizeof(a));
14 for (int i=1;i<=n;i++) scanf("%d",&a[i]);
15 sort(a+1,a+n+1);
16 int i=1;ans=0;
17 while (i<=n)
18 {
19 int s=a[i++];
20 while (i<=n && a[i]<=s+r) i++;
21 int p=a[i-1];
22 while (i<=n && a[i]<=p+r) i++;
23 ans++;
24 }
25 printf("%d\n",ans);
26 scanf("%d%d",&r,&n);
27 }
28 return 0;
29 }
