#![allow(unused_imports, unused_macros)]

use kyoproio::*;
use std::{
    collections::*,
    io::{self, prelude::*},
    iter,
    mem::{replace, swap},
};

fn main() -> io::Result<()> {
    std::thread::Builder::new()
        .stack_size(64 * 1024 * 1024)
        .spawn(solve)?
        .join()
        .unwrap();
    Ok(())
}

fn solve() {
    let stdin = io::stdin();
    let mut kin = KInput::new(stdin.lock());
    let stdout = io::stdout();
    let mut out = io::BufWriter::new(stdout.lock());
    macro_rules! output { ($($args:expr),+) => { write!(&mut out, $($args),+).unwrap(); }; }
    macro_rules! outputln {
        ($($args:expr),+) => { output!($($args),+); outputln!(); };
        () => { output!("\n"); if cfg!(debug_assertions) { out.flush().unwrap(); } }
    }

    let n: usize = kin.input();
    if n == 0 {
        outputln!("1");
        return;
    }

    let ps: Vec<_> = kin
        .iter::<(i32, i32)>()
        .take(n)
        .map(|(x, y)| [x, y])
        .collect();
    let map: HashMap<_, _> = ps.iter().enumerate().map(|(i, &p)| (p, i)).collect();
    let mut uf = UnionFind::new(n);
    for (i, &[x, y]) in ps.iter().enumerate() {
        for dx in -10..=10 {
            for dy in -10..=10 {
                if dx * dx + dy * dy <= 100 {
                    if let Some(&j) = map.get(&[x + dx, y + dy]) {
                        uf.unite(i, j);
                    }
                }
            }
        }
    }

    let mut comps = vec![Vec::new(); n];
    for i in 0..n {
        comps[uf.root(i)].push(ps[i]);
    }

    let mut max = 0;
    for c in comps {
        if !c.is_empty() {
            // eprintln!("{:?}", &c);
            let (i, j) = farest_pair(&c);
            // eprintln!("{:?} - {:?}", c[i], c[j]);
            let [x1, y1] = c[i];
            let [x2, y2] = c[j];
            let x = x2 - x1;
            let y = y2 - y1;
            max = max.max(x * x + y * y);
        }
    }

    let ans = 2. + (max as f64).sqrt();
    outputln!("{}", ans);
}

use std::ops;

pub fn graham_scan<T>(ps: &[[T; 2]]) -> Vec<usize>
where
    T: PartialOrd + ops::Sub<Output = T> + ops::Mul<Output = T> + Copy,
{
    let mut ids: Vec<_> = (0..ps.len()).collect();
    ids.sort_by(|&i, &j| ps[i].partial_cmp(&ps[j]).unwrap());
    let mut hull: Vec<usize> = Vec::new();
    for dir in 0..2 {
        let mut len = dir;
        for &i in &ids {
            let [x2, y2] = ps[i];
            while len >= 2 {
                let [x0, y0] = ps[hull[hull.len() - 2]];
                let [x1, y1] = ps[hull[hull.len() - 1]];
                if (x1 - x0) * (y2 - y0) >= (x2 - x0) * (y1 - y0) {
                    break;
                }
                hull.pop();
                len -= 1;
            }
            hull.push(i);
            len += 1;
        }
        ids.pop();
        ids.reverse();
        ids.pop();
    }
    hull
}

pub fn farest_pair<T>(ps: &[[T; 2]]) -> (usize, usize)
where
    T: PartialOrd + ops::Add<Output = T> + ops::Sub<Output = T> + ops::Mul<Output = T> + Copy,
{
    let norm = |[x0, y0]: [T; 2], [x1, y1]: [T; 2]| (x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0);
    let hull = graham_scan(ps);
    let mut res = (0, 0);
    let mut max = None;
    let mut j = 0;
    for &i in &hull {
        let mut d = norm(ps[i], ps[hull[j]]);
        loop {
            let j_inc = if j + 1 < hull.len() { j + 1 } else { 0 };
            let d_inc = norm(ps[i], ps[hull[j_inc]]);
            if d >= d_inc {
                break;
            }
            d = d_inc;
            j = j_inc;
        }
        if Some(d) > max {
            max = Some(d);
            res = (i, hull[j]);
        }
    }
    res
}

pub struct UnionFind {
    p: Vec<isize>,
}
impl UnionFind {
    pub fn new(n: usize) -> Self {
        Self { p: vec![-1; n] }
    }
    pub fn root(&self, mut u: usize) -> usize {
        while self.p[u] >= 0 {
            u = self.p[u] as usize;
        }
        u
    }
    pub fn size(&self, u: usize) -> usize {
        (-self.p[self.root(u)]) as usize
    }
    pub fn unite(&mut self, u: usize, v: usize) -> bool {
        let mut u = self.root(u);
        let mut v = self.root(v);
        if u == v {
            return false;
        }
        if self.p[u] > self.p[v] {
            swap(&mut u, &mut v);
        }
        self.p[u] += self.p[v];
        self.p[v] = u as isize;
        true
    }
    pub fn is_same(&self, u: usize, v: usize) -> bool {
        self.root(u) == self.root(v)
    }
}

// -----------------------------------------------------------------------------
pub mod kyoproio {
    use std::io::prelude::*;
    pub trait Input {
        fn str(&mut self) -> &str;
        fn input<T: InputParse>(&mut self) -> T {
            T::input(self)
        }
        fn iter<T: InputParse>(&mut self) -> Iter<T, Self> {
            Iter(self, std::marker::PhantomData)
        }
        fn seq<T: InputParse, B: std::iter::FromIterator<T>>(&mut self, n: usize) -> B {
            self.iter().take(n).collect()
        }
    }
    pub struct KInput<R> {
        src: R,
        buf: String,
        pos: usize,
    }
    impl<R: BufRead> KInput<R> {
        pub fn new(src: R) -> Self {
            Self {
                src,
                buf: String::with_capacity(1024),
                pos: 0,
            }
        }
        pub fn src(&mut self) -> &mut R {
            &mut self.src
        }
    }
    impl<R: BufRead> Input for KInput<R> {
        fn str(&mut self) -> &str {
            loop {
                if self.pos >= self.buf.len() {
                    self.pos = 0;
                    self.buf.clear();
                    if self.src.read_line(&mut self.buf).expect("io error") == 0 {
                        return &self.buf;
                    }
                }
                let range = self.pos
                    ..self.buf[self.pos..]
                        .find(|c: char| c.is_ascii_whitespace())
                        .map(|i| i + self.pos)
                        .unwrap_or_else(|| self.buf.len());
                self.pos = range.end + 1;
                if range.end > range.start {
                    return &self.buf[range];
                }
            }
        }
    }
    pub struct Iter<'a, T, I: ?Sized>(&'a mut I, std::marker::PhantomData<*const T>);
    impl<'a, T: InputParse, I: Input + ?Sized> Iterator for Iter<'a, T, I> {
        type Item = T;
        fn next(&mut self) -> Option<T> {
            Some(self.0.input())
        }
    }
    pub trait InputParse: Sized {
        fn input<I: Input + ?Sized>(src: &mut I) -> Self;
    }
    impl InputParse for Vec<u8> {
        fn input<I: Input + ?Sized>(src: &mut I) -> Self {
            src.str().as_bytes().to_owned()
        }
    }
    macro_rules! from_str_impl {
        { $($T:ty)* } => {
            $(impl InputParse for $T {
                fn input<I: Input + ?Sized>(src: &mut I) -> Self {
                    src.str().parse::<$T>().expect("parse error")
                }
            })*
        }
    }
    from_str_impl! {
        String char bool f32 f64 isize i8 i16 i32 i64 i128 usize u8 u16 u32 u64 u128
    }
    macro_rules! tuple_impl {
        ($H:ident $($T:ident)*) => {
            impl<$H: InputParse, $($T: InputParse),*> InputParse for ($H, $($T),*) {
                fn input<I: Input + ?Sized>(src: &mut I) -> Self {
                    ($H::input(src), $($T::input(src)),*)
                }
            }
            tuple_impl!($($T)*);
        };
        () => {}
    }
    tuple_impl!(A B C D E F G);
    #[macro_export]
    macro_rules! kdbg {
        ($($v:expr),*) => {
            if cfg!(debug_assertions) { dbg!($($v),*) } else { ($($v),*) }
        }
    }
}