extern crate primal;
extern crate time;
use std::env;
use time::Duration;
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 mut count = None;
let time = Duration::span(|| {
count = Some(primal::Primes::all().take_while(|x| *x <= max).count())
});
let ns = time.num_nanoseconds().unwrap();
let (s, ns) = (ns / 1_000_000_000, ns % 1_000_000_000);
let time = format!("{}.{:06}", s, ns / 1000);
println!("{} primes below {} in {}s (est: {:?})",
count.unwrap(),
max,
time,
primal::estimate_prime_pi(max as u64));
}