use itertools::Itertools;

#[derive(Debug)]
struct Elf {
    start: usize,
    end: usize,
}

#[derive(Debug)]
struct Pair(Elf, Elf);

impl Elf {
    pub fn new(range: &str) -> Self {
        if let Some((start, end)) = range.to_string().split("-").collect_tuple() {
            let start: usize = start.parse().unwrap();
            let end: usize = end.parse().unwrap();
            Self { start, end }
        } else {
            panic!("Expected two elements");
        }
    }
}

impl Pair {
    pub fn new(line: &str) -> Self {
        if let Some((first, second)) = line.to_string().split(",").collect_tuple() {
            Pair(Elf::new(first), Elf::new(second))
        } else {
            panic!("Expected two elements");
        }
    }
}

impl Pair {
    fn overlaps(&self) -> bool {
        !(self.0.end < self.1.start || self.1.end < self.0.start)
    }
}

fn main() {
    let sum: usize = include_str!("../../input")
        .lines()
        .map(|l| Pair::new(l))
        .map(|p| p.overlaps())
        .filter(|r| *r)
        .count();

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