class UnionFind:
  def __init__(self, n):
    self.node = [-1 for _ in range(n)]

  def root(self, v):
    if self.node[v] < 0:
      return v

    st = []
    while self.node[v] >= 0:
      st.append(v)
      v = self.node[v]

    for u in st:
      self.node[u] = v

    return v

  def size(self, v):
    v = self.root(v)
    return (- self.node[v])

  def same(self, u, v):
    return self.root(u) == self.root(v)

  def unite(self, u, v):
    ru = self.root(u)
    rv = self.root(v)
    if ru == rv:
      return

    du = self.node[ru]
    dv = self.node[rv]
    if du <= dv:
      self.node[rv] = ru
      self.node[ru] += dv
    else:
      self.node[ru] = rv
      self.node[rv] += du

n = int(input())
points = [list(map(int, input().split())) for _ in range(n)]

edges = []
for i in range(n - 1):
  xi, yi = points[i]
  for j in range(i + 1, n):
    xj, yj = points[j]
    d = (xj - xi) ** 2 + (yj - yi) ** 2
    edges.append((d, i, j))

edges.sort(key=lambda x: - x[0])

uf = UnionFind(n)
length = 0
while not uf.same(0, n - 1):
  d, u, v = edges.pop()
  uf.unite(u, v)
  length = max(length, d)

ok = 2 * 10 ** 8
ng = 0
while ok - ng > 1:
  mid = (ok + ng) // 2

  if (mid * 10) ** 2 >= length:
    ok = mid
  else:
    ng = mid

print(ok * 10)