#pragma GCC optimize(3)
#pragma GCC optimize(2)
#include<stdio.h>
#include<cstring>
#include<queue>
using namespace std;
inline int read(){
	int k=0,j=1;char c=getchar();
	while(c<'0'||c>'9'){if(c=='-')j=-1;c=getchar();}
	while(c>='0'&&c<='9')k=k*10+c-'0',c=getchar();
	return k*j;
}
struct pp2{int jx,jy;};queue<pp2>c;
int a[305][305],ans[305][305];
int main(){
	memset(a,0,sizeof(a));
	int m=read();
	for(int i=1;i<=m;i++){
		int j1=read(),j2=read(),t=read();
		if(t==0)t=-1;
		if(a[j1][j2]==0||a[j1][j2]>t)
			a[j1][j2]=t;
		if(j1<=310)
			if(a[j1+1][j2]==0||t<a[j1+1][j2])
				a[j1+1][j2]=t;
		if(j1>=1)
			if(a[j1-1][j2]==0||t<a[j1-1][j2])
				a[j1-1][j2]=t;
		if(j2<=310)
			if(a[j1][j2+1]==0||t<a[j1][j2+1])
				a[j1][j2+1]=t;
		if(j2>=1)
			if(a[j1][j2-1]==0||t<a[j1][j2-1])
				a[j1][j2-1]=t;
	}
	c.push((pp2){0,0});
	while(!c.empty()){
		int i=c.front().jx,j=c.front().jy;
		c.pop();
		if(a[i][j]==0){printf("%d",ans[i][j]);return 0;}
		if(i<311&&(a[i+1][j]==0||a[i+1][j]>ans[i][j]+1)){
			c.push((pp2){i+1,j});ans[i+1][j]=ans[i][j]+1;
		}
		if((a[i-1][j]==0||a[i-1][j]>ans[i][j]+1)&&i>=1){
			c.push((pp2){i-1,j});ans[i-1][j]=ans[i][j]+1;
		}
		if(j<311&&(a[i][j+1]==0||a[i][j+1]>ans[i][j]+1)){
			c.push((pp2){i,j+1});ans[i][j+1]=ans[i][j]+1;
		}
		if((a[i][j-1]==0||a[i][j-1]>ans[i][j]+1)&&j>=1){
			c.push((pp2){i,j-1});ans[i][j-1]=ans[i][j]+1;
		}a[i][j]=-1;
	}
	printf("-1");
	return 0;
}