package test;

import java.util.Scanner;

//完美数

public class exam08 {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        while (scanner.hasNext()) {

            int num = scanner.nextInt();

            System.out.println(count(num));

        }

    }

    public static Boolean isPerfect(int i) {

        boolean isperfect = false;

        int sum = 0;

        for (int j = 1; j <= Math.sqrt(i); j++) {

            // 开方，降低时间复杂度

            // 注意要加上另外一个对应的约数

            if (i % j == 0) {

                sum += j + i / j;

            }

        }

        if ((sum - i) == i) {

            isperfect = true;

        }

        return isperfect;

    }

    public static int count(int n) {

        int sum = 0;// 完美数个数

        if (n >= 0) {

            // 完美数不包括1

            for (int i = 2; i <= n; i++) {

                if (isPerfect(i)) {

                    // System.out.println(i);

                    sum++;

                }

            }

        } else {

            sum = -1;

        }

        return sum;

    }

}