Problem:
Score : 900 points

Problem Statement

There are N pinholes on the xy-plane. The i-th pinhole is located at (x_i,y_i).

We will denote the Manhattan distance between the i-th and j-th pinholes as d(i,j)(=|x_i-x_j|+|y_i-y_j|).

You have a peculiar pair of compasses, called Manhattan Compass.
This instrument always points at two of the pinholes.
The two legs of the compass are indistinguishable, thus we do not distinguish the following two states: the state where the compass points at the p-th and q-th pinholes, and the state where it points at the q-th and p-th pinholes.

When the compass points at the p-th and q-th pinholes and d(p,q)=d(p,r), one of the legs can be moved so that the compass will point at the p-th and r-th pinholes.

Initially, the compass points at the a-th and b-th pinholes.
Find the number of the pairs of pinholes that can be pointed by the compass.

Constraints

2≦N≦10^5

1≦x_i, y_i≦10^9

1≦a < b≦N

When i ≠ j, (x_i, y_i) ≠ (x_j, y_j)

x_i and y_i are integers.

Input

The input is given from Standard Input in the following format:

N a b
x_1 y_1
:
x_N y_N

Output

Print the number of the pairs of pinholes that can be pointed by the compass.

Sample Input 1

5 1 2
1 1
4 3
6 1
5 5
4 8

Sample Output 1

4

Initially, the compass points at the first and second pinholes.

Since d(1,2) = d(1,3), the compass can be moved so that it will point at the first and third pinholes.

Since d(1,3) = d(3,4), the compass can also point at the third and fourth pinholes.

Since d(1,2) = d(2,5), the compass can also point at the second and fifth pinholes.

No other pairs of pinholes can be pointed by the compass, thus the answer is 4.

Sample Input 2

6 2 3
1 3
5 3
3 5
8 4
4 7
2 5

Sample Output 2

4

Sample Input 3

8 1 2
1 5
4 3
8 2
4 7
8 8
3 3
6 6
4 8

Sample Output 3

7

Solution in Rust (1.15.1) (judge verdict: Accepted)

// https://atcoder.jp/contests/arc065/tasks/arc065_c
//
#![allow(unused_imports)]
use std::io::*;
use std::fmt::*;
use std::str::*;
use std::cmp::*;
use std::collections::*;

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_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_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::<Vec<_>>()
    };

    ($iter:expr, [ next / $t:tt ]) => {
        {
            let len = read_value!($iter, usize);
            (0..len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
        }
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

#[allow(unused_macros)]
macro_rules! dvec {
    ($t:expr ; $len:expr) => {
        vec![$t; $len]
    };

    ($t:expr ; $len:expr, $($rest:expr),*) => {
        vec![dvec!($t; $($rest),*); $len]
    };
}

#[allow(unused_macros)]
macro_rules! ifv {
    ($t:expr, $a:expr, $b: expr) => {
        if $t { $a } else { $b }
    }
}

#[allow(unused_macros)]
macro_rules! fill {
    ($t:expr, $v:expr) => {
        for i in 0..$t.len() {
            $t[i] = $v;
        }
    };
}

#[allow(unused_macros)]
macro_rules! join {
    ($t:expr, $glue:expr) => {
        $t.into_iter().map(|w| w.to_string()).collect::<Vec<_>>().join($glue)
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        println!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
    }
}

// ====

#[derive(Debug, Clone)]
struct Treap<T> {
    root: Link<T>
}

impl<T: Ord + Copy + Debug> Treap<T> {
    fn new() -> Self {
        Treap {
            root: None
        }
    }

    fn push(&mut self, v: T) -> bool {
        if self.contains(v) {
            return false;
        }
        let u = self.root.take();
        self.root = Node::push(u, v);
        true
    }

    fn remove(&mut self, v: T) -> bool {
        Node::remove(&mut self.root, v)
    }

    fn len(&self) -> usize {
        Node::sz(&self.root)
    }

    fn min(&self) -> Option<T> {
        Node::min(&self.root)
    }

    fn max(&self) -> Option<T> {
        Node::max(&self.root)
    }

    fn contains(&self, value: T) -> bool {
        Node::contains(&self.root, value)
    }

    fn peek_less(&self, value: T) -> Option<T> {
        Node::peek_less(&self.root, value)
    }

    fn count_less(&self, value: T) -> usize {
        Node::count_less(&self.root, value)
    }

    fn peek_greater(&self, value: T) -> Option<T> {
        Node::peek_greater(&self.root, value)
    }
}

struct XorShift {
    x: i64,
    y: i64,
    z: i64,
    w: i64
}

impl XorShift {
    fn rotate(&mut self) {
        let t = self.x ^ (self.x << 11);
        self.x = self.y;
        self.y = self.z;
        self.z = self.w;
        self.w = (self.w ^ (self.w >> 19)) ^ (t ^ (t >> 8));
    }

    fn next_i64(&mut self) -> i64 {
        self.rotate();
        self.w
    }
}

static mut RAND: XorShift = XorShift {
    x: 123456789i64,
    y: 362436069i64,
    z: 521288629i64,
    w: 88675123i64
};

fn generate_next() -> i64 {
    let x;
    unsafe {
        x = RAND.next_i64();
    }
    x
}

type Link<T> = Option<Box<Node<T>>>;

#[derive(Debug, Clone)]
struct Node<T> {
    value: T,
    size: usize,
    priority: i64,
    left: Link<T>,
    right: Link<T>,
}

impl<T: Ord + Copy + Debug> Node<T> {
    fn new(value: T) -> Self {
        Node {
            value: value,
            size: 1,
            priority: generate_next(),
            left: None,
            right: None
        }
    }

    fn sz(node: &Link<T>) -> usize {
        match node.as_ref() { // TODO: Remove as_ref() after upgrading above 1.26
            None => 0,
            Some(x) => x.size
        }
    }

    fn calc(node: &mut Link<T>) {
        if let Some(x) = node.as_mut() { // TODO: Remove as_mut() after upgrading above 1.26
            x.size = 1 + Node::sz(&x.left) + Node::sz(&x.right);
        }
    }

    fn merge(left: Link<T>, right: Link<T>) -> Link<T> {
        match (left, right) {
            (None, None) => None,
            (None, x) => x,
            (x, None) => x,
            (Some(l), Some(r)) => {
                if l.priority < r.priority {
                    let mut l = l;
                    l.right = Self::merge(l.right.take(), Some(r));
                    let mut l = Some(l);
                    Node::calc(&mut l);
                    l
                } else {
                    let mut r = r;
                    r.left = Self::merge(Some(l), r.left.take());
                    let mut r = Some(r);
                    Node::calc(&mut r);
                    r
                }
            }
        }
    }

    fn min(now: &Link<T>) -> Option<T> {
        match now.as_ref() { // TODO: Remove as_ref() after upgrading above 1.26
            None    => None,
            Some(x) => {
                match x.left.as_ref() { // TODO: Remove as_ref() after upgrading above 1.26
                    None    => Some(x.value),
                    Some(_) => Self::min(&x.left)
                }
            }
        }
    }

    fn max(now: &Link<T>) -> Option<T> {
        match now.as_ref() { // TODO: Remove as_ref() after upgrading above 1.26
            None    => None,
            Some(x) => {
                match x.right.as_ref() { // TODO: Remove as_ref() after upgrading above 1.26
                    None    => Some(x.value),
                    Some(_) => Self::max(&x.right)
                }
            }
        }
    }

    fn contains(now: &Link<T>, value: T) -> bool {
        match now.as_ref() { // TODO: Remove as_ref() after upgrading above 1.26
            None => false,
            Some(x) => {
                match value.cmp(&x.value) {
                    Ordering::Less    => Self::contains(&x.left, value),
                    Ordering::Equal   => true,
                    Ordering::Greater => Self::contains(&x.right, value)
                }
            }
        }
    }

    fn count_less(now: &Link<T>, value: T) -> usize {
        match now.as_ref() { // TODO: Remove as_ref() after upgrading above 1.26
            None => 0,
            Some(x) => {
                match value.cmp(&x.value) {
                    Ordering::Less | Ordering::Equal => {
                        Self::count_less(&x.left, value)
                    },
                    Ordering::Greater => {
                        let w = Self::count_less(&x.right, value);
                        Node::sz(&x.left) + 1 + w
                    }
                }
            }
        }
    }

    fn peek_less(now: &Link<T>, value: T) -> Option<T> {
        match now.as_ref() { // TODO: Remove as_ref() after upgrading above 1.26
            None => None,
            Some(x) => {
                match value.cmp(&x.value) {
                    Ordering::Less | Ordering::Equal => {
                        Self::peek_less(&x.left, value)
                    },
                    Ordering::Greater => {
                        let w = Self::peek_less(&x.right, value);
                        if w == None {
                            Some(x.value)
                        } else {
                            Some(max(w.unwrap(), x.value))
                        }
                    }
                }
            }
        }
    }

    fn peek_greater(now: &Link<T>, value: T) -> Option<T> {
        match now.as_ref() { // TODO: Remove as_ref() after upgrading above 1.26
            None => None,
            Some(x) => {
                match value.cmp(&x.value) {
                    Ordering::Greater | Ordering::Equal => {
                        Self::peek_greater(&x.right, value)
                    },
                    Ordering::Less => {
                        let w = Self::peek_greater(&x.left, value);
                        if w == None {
                            Some(x.value)
                        } else {
                            Some(min(w.unwrap(), x.value))
                        }
                    }
                }
            }
        }
    }

    fn split_at(now: Link<T>, k: usize) -> (Link<T>, Link<T>) {
        match now {
            None => (None, None),
            Some(x) => {
                let mut x = x;
                let lsz = Self::sz(&x.left);
                if k <= lsz {
                    let (nl, nr) = Self::split_at(x.left.take(), k);
                    x.left = nr;
                    let mut x = Some(x);
                    Node::calc(&mut x);
                    (nl, x)
                } else {
                    let (nl, nr) = Self::split_at(x.right.take(), k-1-lsz);
                    x.right = nl;
                    let mut x = Some(x);
                    Node::calc(&mut x);
                    (x, nr)
                }
            },
        }
    }

    fn split_by(now: Link<T>, v: T) -> (Link<T>, Link<T>) {
        match now {
            None => (None, None),
            Some(x) => {
                let mut x = x;
                if v <= x.value {
                    let (nl, nr) = Self::split_by(x.left.take(), v);
                    x.left = nr;
                    let mut x = Some(x);
                    Node::calc(&mut x);
                    (nl, x)
                } else {
                    let (nl, nr) = Self::split_by(x.right.take(), v);
                    x.right = nl;
                    let mut x = Some(x);
                    Node::calc(&mut x);
                    (x, nr)
                }
            },
        }
    }

    fn push(now: Link<T>, new_value: T) -> Link<T> {
        let new_node = Some(Box::new(Node::new(new_value)));
        let (left, right) = Self::split_by(now, new_value);
        Self::merge(Self::merge(left, new_node), right)
    }

    fn remove(now: &mut Link<T>, target_value: T) -> bool {
        let mut both_none = false;
        let w = match now.as_mut() { // TODO: Remove as_mut() after upgrading above 1.26
            None => false,
            Some(x) => {
                if target_value < x.value {
                    Self::remove(&mut x.left, target_value)
                } else if x.value < target_value {
                    Self::remove(&mut x.right, target_value)
                } else {
                    let new_link = Self::merge(x.left.take(), x.right.take());
                    if let Some(node) = new_link {
                        *x = node;
                    } else {
                        both_none = true;
                    }
                    true
                }
            }
        };
        Node::calc(now);
        if both_none {
            now.take();
        }
        w
    }
}

// ====

const INF: i64 = 1e12 as i64;

fn main() {
    input! {
        n: usize, a: usize1, b: usize1,
        pts: [(i64, i64); n]
    };

    let diff = (pts[a].0 - pts[b].0).abs() + (pts[a].1 - pts[b].1).abs();
    let mut pts = pts.into_iter().map(|(x, y)| (x+y, x-y)).collect::<Vec<_>>();
    // debug!(diff, pts);

    let mut xset = Treap::new();
    let mut yset = Treap::new();
    for i in 0..n {
        xset.push((pts[i].0, pts[i].1, i));
        yset.push((pts[i].1, pts[i].0, i));
    }

    let mut visited = vec![false; n];
    let mut deq = VecDeque::new();
    deq.push_back(a);
    while let Some(v) = deq.pop_front() {
        let nx = pts[v].0;
        let ny = pts[v].1;
        for x in vec![nx-diff, nx+diff] {
            let mut y = ny-diff;
            while let Some(v) = xset.peek_greater((x, ny-diff-1, n)) {
                if v.0 > x || v.1 > ny+diff {
                    break;
                }
                xset.remove(v);
                yset.remove((v.1, v.0, v.2));
                assert!(!visited[v.2]);
                visited[v.2] = true;
                deq.push_back(v.2);
            }
        }
        for y in vec![ny-diff, ny+diff] {
            while let Some(v) = yset.peek_greater((y, nx-diff-1, n)) {
                if v.0 > y || v.1 > nx+diff {
                    break;
                }
                yset.remove(v);
                xset.remove((v.1, v.0, v.2));
                assert!(!visited[v.2]);
                visited[v.2] = true;
                deq.push_back(v.2);
            }
        }
    }
    // debug!(visited);

    let mut ans = 0;
    let mut xset = Treap::new();
    let mut yset = Treap::new();
    for i in 0..n {
        if visited[i] {
            xset.push((pts[i].0, pts[i].1, i));
            yset.push((pts[i].1, pts[i].0, i));
        }
    }
    for i in 0..n {
        if !visited[i] {
            continue;
        }
        let nx = pts[i].0;
        let ny = pts[i].1;

        for x in vec![nx-diff, nx+diff] {
            let w = xset.count_less((x, ny+diff+1, 0)) - xset.count_less((x, ny-diff, 0));
            // debug!(i, "lr", x, w);
            ans += w as i64;
        }
        for y in vec![ny-diff, ny+diff] {
            let w = yset.count_less((y, nx+diff, 0)) - yset.count_less((y, nx-diff, n));
            // debug!(i, "du", y, w);
            ans += w as i64;
        }
    }
    println!("{}", ans / 2);
}