use std::io::{BufRead, BufReader};
use std::fs::File;

fn main (){
    // let filename = "../1/input_example.txt";
    let filename = "../1/input.txt";
    let file = BufReader::new(File::open(filename).expect("Unable to open file"));
    let mut accum: u32 = 0;

    let mut list1: Vec<u32> = vec![];
    let mut list2: Vec<u32> = vec![];

    for line in file.lines() {
        let wline = line.unwrap();
        let nums: Vec<&str> = wline.split(' ')
            .filter(|&x| !x.is_empty())
            .collect();

        list1.push(nums[0].parse().unwrap());
        list2.push(nums[1].parse().unwrap());
    }

    list1.sort();
    list2.sort();
    let zlist = list1.into_iter().zip(list2);
    for t in zlist {
        accum += t.0.abs_diff(t.1);
    }

    println!("{}", accum);
}