poj 3069

#include <cstdio>
#include <stack>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <functional>
#include <cstring>
#include <algorithm>
#include <cctype>
#include <string>
#include <map>
#include <iomanip>
#include <cmath>
#define LL long long
#define ULL unsigned long long
#define SZ(x) (int)x.size()
#define Lowbit(x) ((x) & (-x))
#define MP(a, b) make_pair(a, b)
#define MS(arr, num) memset(arr, num, sizeof(arr))
#define PB push_back
#define F first
#define S second
#define ROP freopen("input.txt", "r", stdin);
#define MID(a, b) (a + ((b - a) >> 1))
#define LC rt << 1, l, mid
#define RC rt << 1|1, mid + 1, r
#define LRT rt << 1
#define RRT rt << 1|1
#define BitCount(x) __builtin_popcount(x)
#define BitCountll(x) __builtin_popcountll(x)
#define LeftPos(x) 32 - __builtin_clz(x) - 1
#define LeftPosll(x) 64 - __builtin_clzll(x) - 1
const double PI = acos(-1.0);
const int INF = 0x3f3f3f3f;
using namespace std;
const int N=1010;
const double eps = 1e-8;
const int MAXN = 300 + 10;
const int MOD = 1000007;
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
typedef pair<int, int> pii;
int n,r,a
,vis
;
int slove()
{
    int i=0,cnt=0;
    while(i<n){
        int s=a[i++];
        while(i<n && a[i]<=s+r) i++;
        s=a[i-1];
        while(i<n && a[i]<=s+r) i++;
        cnt++;
    }
    return cnt;
}
int main()
{
    int i,j,t;
    while(~scanf("%d%d",&r,&n) && r!=-1)
    {
        memset(vis,false,sizeof(vis));
        for (j=i=0;j<n;j++) {
            scanf("%d",&t);
            if (!vis[t]){
                a[i++]=t;
                vis[t]=true;
            }
        }
        n=i;  i=0;

        sort(a,a+n);
        int cnt=slove();
        cout<<cnt<<endl;
    }
}