Almost Prime
题目描述
A. Almost Prime
time limit per test
2 secondsmemory limit per test
256 megabytesinput
standard inputoutput
standard outputA 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.
Input
Input contains one integer number n (1≤n≤3000).
Output
Output the amount of almost prime numbers between 1 and n, inclusive.
Examples
Input
10
Output
2
Input
21
Output
8
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