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A7823 | Almost Prime

时间限制1s
内存限制256MB
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题目描述

A number is called almost prime if it has exactly two distinct prime divisors. For example, numbers 6, 18, 24 are almost prime, while 4, 8, 9, 42 are not. Find the amount of almost prime numbers which are between 1 and $n$ , inclusive.

输入格式

Input contains one integer number $n$ ( $1<=n<=3000$ ).

输出格式

Output the amount of almost prime numbers between 1 and $n$ , inclusive.

输入输出样例

输入 #1
10
输出 #1
2
输入 #2
21
输出 #2
8
C++ 编辑器
输入
输出