macro_rules! read {
  ($x:ident, $v:expr, $idx:expr, $type:ty) => {
    let $x:$type = $v[$idx].clone().parse().unwrap();
  };

  ( $($x:ident:$t:ty),* ) => {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let input:Vec<String> = s.trim()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect();
    let mut idx:i64 = -1;
    $(
      idx += 1;
      read!($x, input, idx as usize, $t);
    )*
  };
}

fn main() {
  read!(aw:i64, ab:i64);
  read!(bw:i64, bb:i64);
  read!(c:i64, d:i64);

  let (ab, bb, c) = if ab >= c {
    (ab - c, bb + c, 0)
  } else {
    (0, bb + ab, c - ab)
  };
  let (aw, bw) = (aw - c, bw + c);

  let (aw, bw) = if bw >= d {
    (aw + d, bw - d)
  } else {
    (aw + bw, 0)
  };
  println!("{}", aw);
}