use std::collections::*; use std::io::Write; type Map = BTreeMap; type Set = BTreeSet; type Deque = VecDeque; fn main() { input! { n: usize, p: [(usize, usize); n], } let mut p = p; for p in p.iter_mut() { p.0 += 2 * n; p.1 += 2 * n; } p.sort_by_key(|p| p.0); let s = (0..n).map(|i| p[i].0 - i).max().unwrap(); p.sort_by_key(|p| p.1); let t = (0..n).map(|i| p[i].1 - i).min().unwrap(); if t < s { println!("0"); return; } let mut ans = t - s + 1; if t - s <= 100 { ans = 0; let mut ok = |k: usize| -> bool { p.sort_by_key(|p| p.0); let mut h = BinaryHeap::new(); let mut x = 0; for i in 0..n { while x < n && p[x].0 <= s + i { h.push(!p[x].1); x += 1; } let v = h.pop().unwrap(); if v < s + i { return false; } } true }; ans = (s..=t).filter(|k| ok(*k)).count(); } println!("{}", ans); } // ---------- begin input macro ---------- // reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 #[macro_export] macro_rules! input { (source = $s:expr, $($r:tt)*) => { let mut iter = $s.split_whitespace(); input_inner!{iter, $($r)*} }; ($($r:tt)*) => { let s = { use std::io::Read; let mut s = String::new(); std::io::stdin().read_to_string(&mut s).unwrap(); s }; let mut iter = s.split_whitespace(); input_inner!{iter, $($r)*} }; } #[macro_export] macro_rules! input_inner { ($iter:expr) => {}; ($iter:expr, ) => {}; ($iter:expr, $var:ident : $t:tt $($r:tt)*) => { let $var = read_value!($iter, $t); input_inner!{$iter $($r)*} }; } #[macro_export] macro_rules! read_value { ($iter:expr, ( $($t:tt),* )) => { ( $(read_value!($iter, $t)),* ) }; ($iter:expr, [ $t:tt ; $len:expr ]) => { (0..$len).map(|_| read_value!($iter, $t)).collect::>() }; ($iter:expr, chars) => { read_value!($iter, String).chars().collect::>() }; ($iter:expr, bytes) => { read_value!($iter, String).bytes().collect::>() }; ($iter:expr, usize1) => { read_value!($iter, usize) - 1 }; ($iter:expr, $t:ty) => { $iter.next().unwrap().parse::<$t>().expect("Parse error") }; } // ---------- end input macro ----------