poj 3069 Saruman's Army

#include<iostream>
#include<algorithm>
using namespace std;

int x[1005];

int main() {
int R, N,cnt;
while (scanf("%d%d",&R,&N)){
if (R == N&&N == -1) break;
cnt = 0;
for (int i = 0; i < N; i++)
scanf("%d", &x[i]);
sort(x, x + N);

for (int i=0; i < N;) {
int t = i;
cnt++;
while (x[t] + R >= x[i++]);
i=t = i-2;
while (x[t] + R >= x[i++]);
i--;

}
printf("%d\n", cnt);
}

return 0;
}