code:

#include <iostream>
#include <algorithm>

using namespace std;

int r, n;
int x[1005];

int main()
{
    while ( cin >> r >> n )
    {
        if ( n == -1 )
        {
            break;
        }
        for ( int i = 1 ; i <= n ; ++ i )
        {
            cin >> x[i];
        }
        sort(x + 1, x + n + 1);
        int ans = 0;
        int i = 0;
        int right = 0;
        while ( i <= n )
        {
            i ++;
            if ( x[i] - right > r )
            {
                // cout << x[i] << endl;
                ans ++;
                right = x[i];
            }
        }
        cout << ans << endl;
    }
    return 0;
}

submission