#811. Sieve of Eratosthenes
You get n. Use a sieve to count the prime numbers not greater than n.
### Input
One integer n (1 ≤ n ≤ 10⁶).
### Output
A number.
Examples
Input
19409
Output
2197
Input
305614
Output
26462
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.