import math
I,R=input,range
def J():
	return map(int,I().split())
N=int(I())
P=[0]*N
for i in R(N):
	X,Y,T=J()
	P[i]=[X*X+Y*Y,X,Y,T]
D=[[0]*N for i in R(N)]
for i in R(N):
	p=P[i]
	for j in R(N):
		q=P[j]
		if p[3]==q[3]:u=(q[1]-p[1])**2+(q[2]-p[2])**2
		else:
			s=4*p[0]*q[0]
			r=int(math.sqrt(s))+1
			while s<r*r:r-=1
			u=p[0]-r+q[0]
		D[i][j]=u
M=3200000001
W=[M]*N
W[0]=0
Q={i for i in R(N)}
while len(Q):
	e,w=N,M
	for q in Q:
		if w>W[q]:e,w=q,W[q]
	Q.remove(e)
	for q in Q:W[q]=min(W[q],max(w,D[e][q]))
print(W[N-1])