import sys
import math
input = sys.stdin.readline

"""
Union-Find
ref : https://algo-logic.info/union-find-tree/
"""
class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n
        self.group_members = {}

    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 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 roots(self):
        return [i for i, x in enumerate(self.parents) if(x < 0)]    

    def build_group_members(self):
        self.group_members = { x : [] for x in self.roots() }
        for x in range(self.n):
            self.group_members[self.find(x)].append(x)
        return self.group_members
    

def isqrt(n):
    rn = math.sqrt(n)
    ok = max(0, int(rn - 2))
    ng = int(rn + 2)
    while(abs(ok - ng) > 1):
        mid = (ok + ng) // 2
        if(mid ** 2 <= n):
            ok = mid
        else:
            ng = mid
    return ok

'''
Main Code
'''

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

edges = []
for i in range(n - 1):
    for j in range(i + 1, n):
        x1, y1, t1 = planets[i]
        x2, y2, t2 = planets[j]
        d = (x1 - x2) ** 2 + (y1 - y2) ** 2
        if(t1 != t2):
            r1 = x1 ** 2 + y1 ** 2
            r2 = x2 ** 2 + y2 ** 2
            d = r1 + r2 - isqrt(4 * r1 * r2)
        edges.append((i, j, d))
edges.sort(key=lambda x : x[2])

uni = UnionFind(n)
ans = 0
for x, y, z in edges:
    ans = z
    uni.unite(x, y)
    if not(uni.same(0, n - 1)):
        continue
    break
print(ans)