import sys, math
input = sys.stdin.readline

class UnionFind():
	def __init__(self, n):
		self.n = n
		self.parents = [-1] * n

	def find(self, x):
		if(self.parents[x] < 0):
			return x
		self.parents[x] = self.find(self.parents[x])
		return self.parents[x]

	def unite(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 same(self, x, y):
		return self.find(x) == self.find(y)

	def size(self, x):
		return -self.parents[self.find(x)]

	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 isqrt(n):
	rn = math.sqrt(n)
	ok = int(rn - 2)
	ng = int(rn + 2)
	while(ng - ok > 1):
		k = (ok + ng) >> 1
		if(k * k <= n):
			ok = k
		else:
			ng = k
	return ok


"""
Main Code
"""

n = int(input())
planet = [list(map(int, input().split())) for _ in [0] * n]

edge = []
for i in range(0, n-1):
	for j in range(i+1, n):
		p1 = planet[i]
		p2 = planet[j]
		d = (p1[0] - p2[0]) ** 2 + (p1[1] - p2[1]) ** 2
		if(p1[2] != p2[2]):
			r1 = p1[0] ** 2 + p1[1] ** 2
			r2 = p2[0] ** 2 + p2[1] ** 2
			d = r1 + r2 - isqrt(4 * r1 * r2)
		edge.append((i, j, d))
edge.sort(key = lambda x : x[2])

uni = UnionFind(n)
ans = 0
for a, b, c in edge:
	ans = c
	uni.unite(a, b)
	if(uni.same(0, n-1)):
		break

print(ans)