In a particular social network, friends are automatically allocated to users by the system, and users cannot add friends of their choice on their own. There are currently N users on the social network, labeled from 2 to N + 1.

For every user (where I ranges from 2 to N + 1), the system allocated all the users labeled with multiples of I as the user’s friends (if possible).

One day, all social network users come together for a meeting and form groups such that each person in a group is a direct friend or a friend or a friend of every other person of that group.

Find the total number of groups.

Input Specification:

input: N, denoting the number of users on the social network

Output Specification:

Your function should return the number of groups that can be formed on given conditions:

Example 1:

input1: 5

Output: 2

Explanation:

Two groups will be formed:

2, 3, 4, 6

5

Example 2:

input1: 10

Output: 3

Explanation:

Three groups will be formed:

2, 3, 4, 5, 6, 8, 9, 10

7

11