Count Primes Up To N
Count the primes up to and including N.
Input format
One line with a single integer N (N >= 1).
Output format
Print how many prime numbers are less than or equal to N.
Constraints
- Values fit in a 64-bit signed integer
- Trailing whitespace and a trailing newline are ignored by the judge
Read from stdin, write to stdout. Sample cases below show the exact format.
Sample cases
Example 1
Input
1Expected output
0Example 2
Input
2Expected output
1