import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 7)

N = int(input())
XY = tuple(tuple(map(int, input().split())) for _ in range(N))
if N == 0:
    print(1)
    exit()

root = [-1] * N

def find(i):
    if root[i] < 0:
        return i
    root[i] = find(root[i])
    return root[i]

def same(x, y):
    return find(x) == find(y)

def merge(x, y):
    x = find(x)
    y = find(y)
    if x == y:
        return
    if -root[x] > -root[y]:
        x, y = y, x
    root[x] += root[y]
    root[y] = x


for i, (xi, yi) in enumerate(XY):
    for j, (xj, yj) in enumerate(XY[i + 1:], i + 1):
        if (xi - xj)** 2 + (yi - yj)** 2 <= 100:
            merge(i, j)

ans = 0
for i, (xi, yi) in enumerate(XY):
    for j, (xj, yj) in enumerate(XY[i + 1:], i + 1):
        if same(i, j):
            d = (xi-xj)**2+(yi-yj)**2
            ans = max(ans, d)

print(2.0 + ans ** 0.5)