#include<bits/stdc++.h>
using namespace std;
queue< pair<int,int> >q;
int m,T[50005],X[50005],Y[50005];
int v[400][400],at[400][400],a[400][400];
int dx[5]={0,0,1,-1};
int dy[5]={1,-1,0,0};
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	for(int i=0;i<=400;i++){
		for(int j=0;j<=400;j++)
			a[i][j]=INT_MAX;
			
	}
	cin>>m;
	for(int i=1;i<=m;i++){
		cin>>T[i]>>X[i]>>Y[i];
		if(a[X[i]][Y[i]]>T[i])a[X[i]][Y[i]]=T[i];
		if(a[X[i]+1][Y[i]]>T[i])a[X[i]+1][Y[i]]=T[i];
		if(a[X[i]-1][Y[i]]>T[i])a[X[i]-1][Y[i]]=T[i];
		if(a[X[i]][Y[i]-1]>T[i])a[X[i]][Y[i]-1]=T[i];
		if(a[X[i]][Y[i]+1]>T[i])a[X[i]][Y[i]+1]=T[i];
	}
	memset(v,0,sizeof(v));
	q.push(make_pair(0,0));
	v[0][0]=1;
	at[0][0]=0;
	while(!q.empty()){
		q.pop();
		int x=q.front().first;
		int y=q.front().second;
		for(int i=0;i<4;i++){
			
			int tx=x+dx[i];
			int ty=y+dy[i];
			at[tx][ty]=at[x][y]+1;			
			if(tx>=0&&ty>=0&&v[tx][ty]==0&&a[tx][ty]>at[tx][ty]){
				if(a[tx][ty]==INT_MAX){
					cout<<at[tx][ty];
					return 0;
				}
				else{
					v[tx][ty]=1;
					q.push(make_pair(tx,ty));
				}
			}
		}
	}
	cout<<"--"<<-1;
	return 0;
}