#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include <math.h>
#include <map>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <stack>
#include <algorithm>
#include <array>
#include <unordered_set>
#include <unordered_map>
#include <string>
using namespace std;

bool rcmp(int a, int b) { return a>b; }
typedef long long LL;



int xs[804];
int ys[804];
int ts[804];
char mk[804];
int que[804];
char mp[804][804];
char check(LL r, int n) {
    int i, j, h, t;
    LL dd, dx, dy;
    double v;
    for (i=0; i<n; i++) {
        for (j=i+1; j<n; j++) {
            mp[i][j]=mp[j][i]=0;
            if (ts[i]==ts[j]) {
                dx=xs[i]-xs[j]; dy=ys[i]-ys[j];
                dd=dx*dx+dy*dy;
            } else {
                v=sqrt(xs[i]*xs[i]+ys[i]*ys[i]);
                v-=sqrt(xs[j]*xs[j]+ys[j]*ys[j]);
                dd=v*v;
                if (v*v-dd>1e-12) dd++;
            }
            if (dd<=r) mp[i][j]=mp[j][i]=1;
        } if (mp[0][n-1]) return 1;
    }
    for (i=0; i<n; i++) mk[i]=0;
    h=t=0; que[h++]=0; mk[0]=1;
    while(t<h) {
        i=que[t++];
        for (j=0; j<n; j++) if (j!=i&&mp[i][j]&&mk[j]==0) {
            mk[j]=1; que[h++]=j;
        }
    }
    return mk[n-1];
}

int main() {
    int n, i;
    LL r, nr, d;
    LL dx, dy;
    scanf("%d", &n);
    for (i=0; i<n; i++) scanf("%d %d %d", &xs[i], &ys[i], &ts[i]);
    dx=xs[0]-xs[n-1];
    dy=ys[0]-ys[n-1];
    r=-1; d=dx*dx+dy*dy;
    while(d) {
        while(1) {
            nr=r+d;
            if (check(nr, n)) break;
            r=nr;
        }
        d>>=1;
    }
    r++; printf("%lld\n", r);

    return 0;
}