from collections import defaultdict
from itertools import combinations
import math


class UnionFind:
    def __init__(self, n):
        self.par = list(range(n))

    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return
        self.par[x] = y


def convex_hull(P):
    def veccross(A, B, C):
        return (C[0] - A[0]) * (B[1] - A[1]) - (C[1] - A[1]) * (B[0] - A[0])

    n = len(P)
    if n <= 2:
        return list(range(n))

    ps = [None] * n
    for i in range(n):
        ps[i] = (P[i], i)
    ps.sort()

    k = 0
    res = [0] * (n * 2)

    for i in range(n):
        while k > 1 and veccross(P[res[k - 2]], P[res[k - 1]], ps[i][0]) <= 0:
            k -= 1
        res[k] = ps[i][1]
        k += 1

    t = k
    for i in range(n - 2, -1, -1):
        while k > t and veccross(P[res[k - 2]], P[res[k - 1]], ps[i][0]) <= 0:
            k -= 1
        res[k] = ps[i][1]
        k += 1

    return res[:k - 1]


def m_dist(g, xs, ys):
    ps = [(xs[i], ys[i]) for i in g]
    os = convex_hull(ps)
    ma = 0
    for i, j in combinations(os, 2):
        ma = max(ma, (ps[i][0] - ps[j][0]) ** 2 + (ps[i][1] - ps[j][1]) ** 2)
    return ma


def solve():
    N = int(input())
    XS = [0] * N
    YS = [0] * N

    B = defaultdict(list)

    def b(x, y):
        if 0 <= x <= 2000 and 0 <= y <= 2000:
            return B[x, y]
        else:
            return []

    ds = [(-1, -1), (0, -1), (1, -1), (-1, 0), (0, 0), (1, 0), (-1, 1), (0, 1), (1, 1)]

    uf = UnionFind(N)

    for i in range(N):
        x, y = map(int, input().split())
        x += 10000
        y += 10000
        XS[i] = x
        YS[i] = y

        x10 = x // 10
        y10 = y // 10

        for dx, dy in ds:
            for j in b(x10 + dx, y10 + dy):
                if (x - XS[j]) ** 2 + (y - YS[j]) ** 2 <= 100:
                    uf.union(i, j)
        B[x10, y10].append(i)

    gd = defaultdict(list)
    for i in range(N):
        gd[uf.find(i)].append(i)

    if len(gd) == 0:
        print(1)
    else:
        ma = 0
        for g in gd.values():
            ma = max(ma, m_dist(g, XS, YS))
        print(math.sqrt(ma) + 2)


if __name__ == '__main__':
    solve()