import java.util.Scanner;

 public class Lamp {

     public static void main(String[] args) {

         System.out.println("请输入长廊里灯的数量：");

         Scanner s = new Scanner(System.in);

         int n = s.nextInt();

         s.close();

         if((n < 1) || (n > 65535))

         {

             System.out.println("输入数值超出范围！");

         }

         else

         {

             System.out.println("长廊里有 "+getLampNum(n)+" 盏灯亮着");

         }

     }

     private static int getLampNum(int n) {

         int ret = 0;

         boolean[] flag = new boolean[n];

         //初始化电灯，全部关着

         for(int i = 0; i < n; i++)

         {

             flag[i] = false;

         }

         //拉灯操作，true为亮，灭为false

         for(int i = 1; i <= n; i++)

         {

             for(int j = i; j <= n; j++)

             {

                 if(0 == j%i)

                 {

                     flag[j-1] = !flag[j-1];

                 }

             }

         }

         //找出所有亮的灯

         for(int i = 0; i < n; i++)

         {

             if(flag[i])

             {

                 ret++;

             }

         }

         return ret;

     }

 }