from collections import deque
import math

n = int(input())

if n == 0:
  print("1.0")
  exit()

dist = [[1 << 60 for _ in range(n)] for _ in range(n)]

points = [list(map(int, input().split())) for _ in range(n)]
g = [[] for _ in range(n)]
for i in range(n - 1):
  xi, yi = points[i]
  for j in range(i + 1, n):
    xj, yj = points[j]
    d2 = (xj - xi) ** 2 + (yj - yi) ** 2
    dist[i][j] = d2
    if d2 <= 10 ** 2:
      g[i].append(j)
      g[j].append(i)

par = [None for _ in range(n)]
for src in range(n):
  if not par[src] is None:
    continue
  par[src] = src
  dq = deque()
  dq.append(src)
  while len(dq) > 0:
    cur = dq.popleft()
    for nxt in g[cur]:
      if not par[nxt] is None:
        continue
      par[nxt] = src
      dq.append(nxt)

ans = 0
for i in range(n - 1):
  for j in range(i + 1, n):
    if par[i] == par[j]:
      ans = max(ans, dist[i][j])

ans = math.sqrt(ans) + 2
print(ans)