#WA#

########################################
from heapq import heappush, heappop
def dijkstra( G, s, INF=10 ** 18):
    """
    https://tjkendev.github.io/procon-library/python/graph/dijkstra.html
    O((|E|+|V|)log|V|)
    V: 頂点数
    G[v] = [(nod, cost)]:
        頂点vから遷移可能な頂点(nod)とそのコスト(cost)
    s: 始点の頂点"""

    N=len(G)
    N+=1
    dist = [INF] * N
    hp = [(0, s)]  # (c, v)
    dist[s] = 0
    while hp:
        c, v = heappop(hp)  #vまで行くコストがc
        if dist[v] < c:
            continue
        for u, cost in G[v]:
            if max(dist[v] , cost) < dist[u]:
                dist[u] = max(dist[v] , cost)
                heappush(hp, (dist[u], u))
    return dist
##################################################



n=int(input())
x=[0]
y=[0]
t=[0]
for i in range(n):
    a,b,c=map(int,input().split())
    x.append(a)
    y.append(b)
    t.append(c)
def cost(i,j):
    if False:
        return (x[i]-x[j])**2+(y[i]-y[j])**2
    else:
        ri2 = x[i] ** 2 + y[i] ** 2
        rj2 = x[j] ** 2 + y[j] ** 2
        def f(s):
            if s<0:return 0
            if ri2+rj2-s<0:return 1
            return (ri2+rj2-s)**2<=4*ri2*rj2
        ng=int(abs(ri2**0.5-rj2**0.5)**2)-2
        ok=ng+4
        while ok-ng>1:
            mid=(ok+ng)//2
            if f(mid):ok=mid
            else:ng=mid
        return ok


root=[[] for i in range(n+5)]
for i in range(1,n+1):
    for j in range(i+1,n+1):
        c=cost(i,j)
        root[i].append((j,c))
        root[j].append((i,c))

print(dijkstra(root,1)[n])