use std::env;
use std::time::Instant;
fn main() {
let mut args = env::args();
let max = args
.nth(1).and_then(|s| s.parse::<f64>().ok().map(|x| x as usize))
.unwrap_or(1_000_000);
let start = Instant::now();
let count = primal_slowsieve::Primes::sieve(max).count_upto(max);
let time = start.elapsed();
println!("{} primes below {} in {:?} (est: {:?})",
count, max, time, primal::estimate_prime_pi(max as u64));
}