use std::cmp::{min, max};

fn main() {
    let mut awab = String::new();
    std::io::stdin().read_line(&mut awab).ok();
    let awab: Vec<isize> = awab.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let mut bwbb = String::new();
    std::io::stdin().read_line(&mut bwbb).ok();
    let bwbb: Vec<isize> = bwbb.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let mut cd = String::new();
    std::io::stdin().read_line(&mut cd).ok();
    let cd: Vec<isize> = cd.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let mut aw = awab[0];
    let     ab = awab[1];
    let mut bw = bwbb[0];
    let c  = cd[0];
    let d  = cd[1];

    let movew1 = max(c-ab,0);
    aw -= movew1;
    bw += movew1;
    let movew2 = min(d, bw);

    println!("{}", aw + movew2);
}