import math
import heapq

n = int(input())
nodes = []
for _ in range(n):
    x, y, t = map(int, input().split())
    r = math.hypot(x, y)
    nodes.append((x, y, t, r))

adj = [[] for _ in range(n + 1)]  # 1-based indexing

for i in range(n):
    x1, y1, t1, r1 = nodes[i]
    for j in range(i + 1, n):
        x2, y2, t2, r2 = nodes[j]
        if t1 != t2:
            s_ij = (r1 - r2) ** 2
        else:
            dx = x1 - x2
            dy = y1 - y2
            s_ij = dx * dx + dy * dy
        adj[i + 1].append((j + 1, s_ij))
        adj[j + 1].append((i + 1, s_ij))

INF = float('inf')
dist = [INF] * (n + 1)
dist[1] = 0.0
heap = []
heapq.heappush(heap, (0.0, 1))

while heap:
    current_max, u = heapq.heappop(heap)
    if u == n:
        break
    if current_max > dist[u]:
        continue
    for v, s in adj[u]:
        new_max = max(current_max, s)
        if new_max < dist[v]:
            dist[v] = new_max
            heapq.heappush(heap, (new_max, v))

ans = math.ceil(dist[n])
print(ans)