import math
import heapq

def main():
    n = int(input())
    planets = []
    for _ in range(n):
        x, y, t = map(int, input().split())
        r = math.hypot(x, y)
        planets.append((x, y, t, r))
    
    # Precompute all pairs' minimal distance squared
    edges = [[0.0] * n for _ in range(n)]
    for i in range(n):
        xi, yi, ti, ri = planets[i]
        for j in range(n):
            if i == j:
                continue
            xj, yj, tj, rj = planets[j]
            if ti != tj:
                d_sq = (ri - rj) ** 2
            else:
                dx = xi - xj
                dy = yi - yj
                d_sq = dx * dx + dy * dy
            edges[i][j] = d_sq
    
    # Dijkstra's algorithm to find the minimal maximum edge weight
    INF = float('inf')
    dist = [INF] * n
    dist[0] = 0.0  # Starting at planet 1 (index 0)
    heap = []
    heapq.heappush(heap, (0.0, 0))
    
    while heap:
        current_max, u = heapq.heappop(heap)
        if u == n - 1:
            print(math.ceil(current_max))
            return
        if current_max > dist[u]:
            continue
        for v in range(n):
            if v == u:
                continue
            new_max = max(current_max, edges[u][v])
            if new_max < dist[v]:
                dist[v] = new_max
                heapq.heappush(heap, (new_max, v))
    
    # If no path found (shouldn't happen as per problem constraints)
    print(-1)

if __name__ == "__main__":
    main()