#include<bits/stdc++.h> 
using namespace std;
int m,visi[550][550],safe[550][550],ways[10][2]={{1,0},{-1,0},{0,1},{0,-1}},x,y,t,ans=0x7f;
struct node{
	int xx,yy,steps;
};
queue<node>q;
int bfs()
{
	node now,nex;
	now.xx=1,now.yy=1,now.steps=0; 
	visi[1][1]=0;
	q.push(now);
	while(!q.empty())
	{
		now=q.front();
		q.pop();
		if(safe[now.xx][now.yy]==0x7f7f7f7f)
			return ans=now.steps;
		for(int i=0;i<4;i++)
		{
			if(now.xx+ways[i][0]>=0&&now.yy+ways[i][1]>=0)
			{
				nex.xx=now.xx+ways[i][0],nex.yy=now.yy+ways[i][1],nex.steps=now.steps+1;
				if(safe[nex.xx][nex.yy]>nex.steps&&visi[nex.xx][nex.yy])
				{
					q.push(nex);
					visi[nex.xx][nex.yy]=0;
				}
			}
		}
	}
}
signed main()
{
	scanf("%d",&m);
	for(int i=0;i<=500;i++)
		for(int j=0;j<=500;j++)
			visi[i+1][j+1]=1;
	memset(safe,0x7f,sizeof(safe));
	for(int j=1;j<=m;j++)
	{
		scanf("%d%d%d",&x,&y,&t);
		safe[x+1][y+1]=min(safe[x+1][y+1],t);
		for(int i=0;i<4;i++)
			if(x+ways[i][0]+1>0&&y+ways[i][1]+1>0)
			{
				safe[x+ways[i][0]+1][y+ways[i][1]+1]=min(safe[x+ways[i][0]+1][y+ways[i][1]+1],t);
			} 
	}
	bfs();
	if(ans==0x7f)
		cout<<-1;
	else
		cout<<ans;
	return 0;
}