/* -*- coding: utf-8 -*-
 *
 * 2179.cc:  No.2179 Planet Traveler - yukicoder
 */

#include<cstdio>
#include<cmath>
#include<queue>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_N = 800;
const long long MAX_S = 3200000000LL;

/* typedef */

typedef long long ll;
typedef queue<int> qi;

/* global variables */

int xs[MAX_N], ys[MAX_N], ts[MAX_N];
double rs[MAX_N];
ll ds[MAX_N][MAX_N];
bool used[MAX_N];

/* subroutines */

inline ll dist2(int dx, int dy) { return (ll)dx * dx + (ll)dy * dy; }

bool check(int n, ll s) {
  fill(used, used + n, false);
  used[0] = true;

  qi q;
  q.push(0);

  while (! q.empty()) {
    int u = q.front(); q.pop();
    if (u == n - 1) return true;

    for (int v = 0; v < n; v++)
      if (! used[v] && ds[u][v] <= s) {
	used[v] = true;
	q.push(v);
      }
  }

  return false;
}

/* main */

int main() {
  int n;
  scanf("%d", &n);

  for (int i = 0; i < n; i++) {
    scanf("%d%d%d", xs + i, ys + i, ts + i);
    rs[i] = sqrt(dist2(xs[i], ys[i]));
  }

  for (int i = 0; i < n; i++)
    for (int j = i + 1; j < n; j++) {
      if (ts[i] != ts[j]) {
	double dr = rs[j] - rs[i];
	ds[i][j] = ds[j][i] = ceil(dr * dr);
      }
      else
	ds[i][j] = ds[j][i] = dist2(xs[j] - xs[i], ys[j] - ys[i]);
    }

  ll s0 = -1, s1 = MAX_S;
  while (s0 + 1 < s1) {
    ll s = (s0 + s1) / 2;
    if (check(n, s)) s1 = s;
    else s0 = s;
  }

  printf("%lld\n", s1);

  return 0;
}