use std::env;
use std::time::Instant;
fn main() {
let mut args = env::args();
let n = 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 prime = primal::Primes::all().nth(n - 1).unwrap();
let time = start.elapsed();
println!("{}th prime is {} (est: {:?})\ntotal: {:?}",
n, prime, primal::estimate_nth_prime(n as u64), time);
}