from heapq import heappop,heappush

n = int(input())
XYT = [list(map(int,input().split())) for i in range(n)]

eps = 10**(-6)
dist = [[0]*n for i in range(n)]
for i in range(n):
    for j in range(i):
        x,y,t = XYT[i]
        nx,ny,nt = XYT[j]
        if t == nt:
            d = (x-nx)**2+(y-ny)**2
            
        else:
            r1 = (x**2+y**2)**0.5
            r2 = (nx**2+ny**2)**0.5
            d = (r1-r2)**2
            dint = int(d)
            if dint+eps >= d:
                d = dint
            else:
                d = dint+1

        dist[i][j] = dist[j][i] = d

inf = 10**20
dis = [inf]*n

dis[0] = 0
h = [[0,0]]

while h:
    d,now = heappop(h)
    if dis[now] != d:
        continue
    for j in range(n):
        if now == j:
            continue
        dnex = max(d,dist[now][j])
        if dis[j] > dnex:
            dis[j] = dnex
            heappush(h,[dnex,j])
print(dis[-1])