use std::collections::BinaryHeap;
use std::io;

fn main() -> io::Result<()> {
    let mut l1 = BinaryHeap::<u64>::new();
    let mut l2 = BinaryHeap::<u64>::new();
    for line in io::stdin().lines() {
        let line = line?;
        let parts: Vec<&str> = line.trim().split_whitespace().collect();
        let (n1, n2) = (parts[0], parts[1]);
        l1.push(n1.parse().unwrap());
        l2.push(n2.parse().unwrap());
    }
    let l1 = l1.into_sorted_vec();
    let l2 = l2.into_sorted_vec();
    let mut sum = 0;
    for (n1, n2) in l1.into_iter().zip(l2.into_iter()) {
        sum += n1.abs_diff(n2);
    }
    println!("{}", sum);
    Ok(())
}