use std::cmp::*; use std::io::{Write, BufWriter}; // https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 macro_rules! input { ($($r:tt)*) => { let stdin = std::io::stdin(); let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock())); let mut next = move || -> String{ bytes.by_ref().map(|r|r.unwrap() as char) .skip_while(|c|c.is_whitespace()) .take_while(|c|!c.is_whitespace()) .collect() }; input_inner!{next, $($r)*} }; } macro_rules! input_inner { ($next:expr) => {}; ($next:expr,) => {}; ($next:expr, $var:ident : $t:tt $($r:tt)*) => { let $var = read_value!($next, $t); input_inner!{$next $($r)*} }; } macro_rules! read_value { ($next:expr, ( $($t:tt),* )) => { ($(read_value!($next, $t)),*) }; ($next:expr, [ $t:tt ; $len:expr ]) => { (0..$len).map(|_| read_value!($next, $t)).collect::>() }; ($next:expr, $t:ty) => ($next().parse::<$t>().expect("Parse error")); } // Port from https://satanic0258.github.io/snippets/data-structure/SegmentMap.html #[derive(Clone, Debug, Default)] struct Segs { s: std::collections::BTreeMap, } impl Segs { fn new() -> Self { Default::default() } fn get(&self, x: i64) -> Option<(i64, i64)> { if let Some((&l, &r)) = self.s.range(..=x).rev().next() { if x < r { Some((l, r)) } else { None } } else { None } } // adds [l, r). fn add(&mut self, mut l: i64, mut r: i64) { assert!(l <= r); if l == r { return; } fn deref((&x, &y): (&i64, &i64)) -> (i64, i64) { (x, y) } let mut p = self.s.range(..=l).rev().next().map(deref); if p.is_none() { p = self.s.iter().next().map(deref); } while let Some((a, b)) = p { if a > r { break; } if b >= l { l = std::cmp::min(l, a); r = std::cmp::max(r, b); self.s.remove(&a); } p = self.s.range(a + 1..).next().map(deref); } self.s.insert(l, r); } #[allow(unused)] fn each(&self, f: F) { for (&x, &y) in &self.s { f(x, y); } } } fn main() { let out = std::io::stdout(); let mut out = BufWriter::new(out.lock()); macro_rules! puts {($($format:tt)*) => (let _ = write!(out,$($format)*););} input! { _d: i64, q: usize, ab: [(i64, i64); q], } let mut segs = Segs::new(); let mut ma = 0; for &(a, b) in &ab { segs.add(a, b + 1); if let Some((l, r)) = segs.get(a) { ma = max(ma, r - l); } puts!("{}\n", ma); } }