class UF:
    def __init__(self,n):
        self.p = [-1]*n
    def f(self,x):
        if self.p[x]<0: return x
        else: self.p[x] = self.f(self.p[x]); return self.p[x]
    def u(self,x,y):
        x = self.f(x); y = self.f(y)
        if x==y: return
        if -self.p[x]<-self.p[y]: x,y = y,x
        self.p[x] += self.p[y]; self.p[y] = x
    def s(self,x,y): return self.f(x) == self.f(y)
n = int(input())
xyt = [tuple(map(int,input().split())) for _ in range(n)]
dij = []
for i,(xi,yi,ti) in enumerate(xyt):
    for j,(xj,yj,tj) in enumerate(xyt):
        if i==j: continue
        if ti==tj: d = (xi-xj)**2+(yi-yj)**2
        else: d = (xi**2+yi**2+xj**2+yj**2)-int((4*(xi**2+yi**2)*(xj**2+yj**2))**0.5)
        dij.append((d,i,j))
uf = UF(n)
s = 0
for d,i,j in sorted(dij):
    if not uf.s(i,j): uf.u(i,j); s = d
    if uf.s(0,n-1): break
print(s)