#[allow(unused_imports)]
use proconio::{
    input,
    marker::{Bytes, Chars, Usize1},
};
fn main() {
    input! {
        a: isize,
        b: isize,
        c: isize,
        d: isize,
    }
    let res = if a == c || b == d || (a - c).abs() + (b - d).abs() <= 3 {
        1
    } else {
        2
    };
    println!("{}", res);
}