import itertools as iter
import collections as coll
import heapq as hq
import bisect as bis
from decimal import Decimal as dec
from functools import cmp_to_key
import math
import sys
#import pypyjit
#pypyjit.set_param('max_unroll_recursion=-1')
sys.setrecursionlimit(10 ** 6)
inp = sys.stdin.readline
input = lambda : inp().rstrip()
getN = lambda : int(inp())
getNs = lambda : map(int, inp().split())
getList = lambda :list(map(int, inp().split()))
getStrs = lambda n : [input() for _ in [0] * n]
def yexit(): print("Yes"); exit(0)
def nexit(): print("No"); exit(0)
pi = 3.141592653589793
mod = 1000000007
MOD = 998244353
INF = 4611686018427387903
dx = [1, 0, -1, 0];	dy = [0, 1, 0, -1]
#di = coll.defaultdict(int)


"""
Main Code
"""

n = getN()
planet = [getList() for _ in [0]*n]

def isqrt(n):
	ok = 0
	ng = n + 1
	while(ng - ok > 1):
		mid = (ok + ng) >> 1
		if(mid * mid <= n):
			ok = mid
		else:
			ng = mid
	return ok

route = [[] for _ in [0]*n]
for i in range(n-1):
	for j in range(i+1, n):
		p1 = planet[i]
		p2 = planet[j]
		dist = (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
			dist = r1 + r2 - isqrt(4 * r1 * r2)
		route[i].append((j,dist))
		route[j].append((i,dist))

dp = [10 ** 18] * n
dp[0] = 0
que = [(0, 0)]
while(que):
	d_now, v_now = hq.heappop(que)
	if(v_now == n-1):
		print(d_now)
		exit(0)
	for v_next, dist in route[v_now]:
		d_next = max(d_now, dist)
		if(d_next >= dp[v_next]):
			continue
		dp[v_next] = d_next
		hq.heappush(que, (d_next, v_next))