#include<iostream>
#include<queue>
#include<cmath>
using namespace std;
int N;
int X[800],Y[800],T[800];
long D[800][800];
long dist[800];
bool vis[800];
int main()
{
	cin>>N;
	for(int i=0;i<N;i++)cin>>X[i]>>Y[i]>>T[i];
	for(int i=0;i<N;i++)for(int j=i+1;j<N;j++)
	{
		if(T[i]!=T[j])
		{
			long I=X[i]*X[i]+Y[i]*Y[i];
			long J=X[j]*X[j]+Y[j]*Y[j];
			//I+J-2sqrt(IJ)<=S
			long S=I+J-(long)(2*sqrt(I*J))-5;
			if(S<0)S=0;
			while((I+J-S)*(I+J-S)>4*I*J)S++;
			D[i][j]=D[j][i]=S;
		}
		else
		{
			D[i][j]=D[j][i]=(long)(X[i]-X[j])*(X[i]-X[j])+(long)(Y[i]-Y[j])*(Y[i]-Y[j]);
		}
	}
	for(int i=1;i<N;i++)dist[i]=9e18;
	dist[0]=0;
	while(true)
	{
		int u=-1;
		for(int v=0;v<N;v++)if(!vis[v]&&(u==-1||dist[u]>dist[v]))u=v;
		if(u==-1)break;
		vis[u]=true;
		for(int v=0;v<N;v++)if(!vis[v])dist[v]=min(dist[v],max(dist[u],D[u][v]));
	}
	cout<<dist[N-1]<<endl;
}