nt prim[MAX] = {1}, s[MAX],l=0;
void prime()
{
	int i, j;
	memset(prim, 0, sizeof(prim));
	for (i = 2; i < MAX; i++)
	{
		if (prim[i])continue;
		for (j = i + i; j < MAX; j += i)
		{
			prim[j] = 1;
		}
		s[l++] = i;
	}
	//s里面保存的是2-MAX的素数
}