#[allow(unused_imports)]
use std::cmp::{Ordering};

#[allow(unused_imports)]
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};

#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};

#[allow(unused_imports)]
use std::iter::FromIterator;

#[allow(unused_macros)]
macro_rules! min {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::min($x, min!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! max {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::max($x, max!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! get { 
    ([$t: ty]) => { 
        { 
            let mut line = String::new(); 
            stdin().read_line(&mut line).unwrap(); 
            line.split_whitespace().map(|t|t.parse::<$t>().unwrap()).collect::<Vec<_>>()
        }
    };
    ([$t: ty];$n: expr) => {
        (0..$n).map(|_|get!([$t])).collect::<Vec<_>>()
    };
    ($t: ty) => {
        {
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            line.trim().parse::<$t>().unwrap()
        }
    };
    ($($t: ty),*) => {
        { 
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            let mut iter = line.split_whitespace();
            ($(iter.next().unwrap().parse::<$t>().unwrap(),)*)
        }
    };
    ($t: ty; $n: expr) => {
        (0..$n).map(|_|get!($t)).collect::<Vec<_>>()
    };
    ($($t: ty),*; $n: expr) => {
        (0..$n).map(|_|get!($($t),*)).collect::<Vec<_>>()
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        #[cfg(debug_assertions)]
        writeln!(&mut std::io::stderr(), concat!("[DEBUG] ", $(stringify!($a), "={:?} "),*), $($a),*).unwrap();
    }
}

const BIG_STACK_SIZE: bool = true;

#[allow(dead_code)]
fn main() {
    use std::thread;
    if BIG_STACK_SIZE {
        thread::Builder::new()
            .stack_size(32 * 1024 * 1024)
            .name("solve".into())
            .spawn(solve)
            .unwrap()
            .join()
            .unwrap();
    } else {
        solve();
    }
}

fn ternary_search<F>(l: f64, r: f64, crit: F) -> f64 
    where F: Fn(f64) -> f64 
{
    let mut l = l;
    let mut r = r;
    let epsilon = 1e-7;
    while r-l > epsilon {
        let nl = l+(r-l)/3.0;
        let nr = l+2.0*(r-l)/3.0;
        if crit(nl) > crit(nr) {
            l = nl;
        } else {
            r = nr;
        }
    }
    l
}

fn solve() {
    let n = get!(usize);
    let xy = get!(f64, f64; n);

    let max_dist = |x_c: f64, y_c: f64| -> f64 {
        let mut mx = 0.0f64;
        for &(x,y) in &xy {
            mx = mx.max((x-x_c).powf(2.0)+(y-y_c).powf(2.0));
        }
        mx
    };

    let crit = |x: f64| -> f64 {
        let max_dist2 = |y_c: f64| -> f64 {
            max_dist(x, y_c)
        };
        let y = ternary_search(0.0, 1000.0, max_dist2);
        max_dist(x, y)
    };

    let x = ternary_search(0.0, 1000.0, crit);
    debug!(x);

    let max_dist2 = |y_c: f64| -> f64 {
        max_dist(x, y_c)
    };
    let y = ternary_search(0.0, 1000.0, max_dist2);
    println!("{}", max_dist(x, y).sqrt());
}


Measured memory_bytes: 8572