import sys
sys.setrecursionlimit(10**6)
class UnionFind():
  def __init__(self, n):
    self.n = n
    self.parents = [-1] * n
  def find(self, x):
    if self.parents[x] < 0:
      return x
    else:
      self.parents[x] = self.find(self.parents[x])
      return self.parents[x]
  def union(self, x, y):
    x = self.find(x)
    y = self.find(y)
    if x == y:
      return
    if self.parents[x] > self.parents[y]:
      x, y = y, x
    self.parents[x] += self.parents[y]
    self.parents[y] = x
  def size(self, x):
    return -self.parents[self.find(x)]
  def same(self, x, y):
    return self.find(x) == self.find(y)
  def members(self, x):
    root = self.find(x)
    return [i for i in range(self.n) if self.find(i) == root]
  def roots(self):
    return [i for i, x in enumerate(self.parents) if x < 0]
  def group_count(self):
    return len(self.roots())
  def all_group_members(self):
    return {r: self.members(r) for r in self.roots()}
  def __str__(self):
    return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())

N=int(input())
P=[list(map(int,input().split())) for _ in range(N)]
d=[]
for i in range(N):
  Xi,Yi,Ti=P[i]
  x=Xi**2+Yi**2
  for j in range(i+1,N):
    Xj,Yj,Tj=P[j]
    y=Xj**2+Yj**2
    if Ti==Tj: d.append(((Xi-Xj)**2+(Yi-Yj)**2,i,j))
    else:
      l,r=-1,2*(x+y)
      while r-l>1:
        mid=(l+r)//2
        if mid*(mid-2*(x+y))<=4*x*y-x**2-y**2-2*x*y: r=mid
        else: l=mid
      d.append((r,i,j))
d.sort()
uf=UnionFind(N)
for i in range(len(d)):
  dis,s,t=d[i]
  uf.union(s,t)
  if uf.find(0)==uf.find(N-1):
    print(dis)
    break