#include<iostream>

 #include<cstdio>

 #include<queue>

 #include<cstring>

 #include<algorithm>

 #include<cmath>

 #include<stack>

 #define lson l, m, rt<<1

 #define rson m+1, r, rt<<1|1

 #define IO ios::sync_with_stdio(false);cin.tie(0);

 #define INF 0x3f3f3f3f

 typedef unsigned long long ll;

 using namespace std;

 int a[][], vis[][];

 int dir[][] = {, , , -, , , -, };

 typedef struct{

     int a, b;

     int step;

 }Node;

 Node node;

 void bfs()

 {

     queue<Node> q;

     node.a = ; node.b = ;

     node.step = ;

     q.push(node);

     vis[][] = ;

     while(!q.empty()){

         Node t = q.front(), p;

         if(a[t.a][t.b] == INF){

             cout << t.step << endl;

             break;

         }

         for(int i = ; i < ; i++){

             int tx = t.a + dir[i][];

             int ty = t.b + dir[i][];

             if(tx>=&&ty>=&&!vis[tx][ty]){

                 if(t.step+<a[tx][ty]){

                     p.a = tx; p.b = ty;

                     p.step = t.step+;

                     vis[tx][ty] = ;

                     q.push(p);

                 }

             }

         }

         q.pop();

     }

     if(q.empty()){

         cout << "-1" << endl;

     }

 }

 int main()

 {

     IO;

     int m, x, y, t;

     memset(vis, , sizeof(vis));

     for(int i = ; i < ; i++){

         for(int j = ; j < ; j++){

             a[i][j] = INF;

         }

     }

     cin >> m;

     for(int i = ; i < m; i++){

         cin >> x >> y >> t;

         a[x][y] = min(a[x][y], t);

         for(int j = ; j < ; j++){

             int tx = x + dir[j][];

             int ty = y + dir[j][];

             if(tx>=&&ty>=){

                 a[tx][ty] = min(a[tx][ty], t);

             }

         }

     }

     /*for(int i = 0; i < 10; i++){

         for(int j = 0; j < 10; j++){

             cout << a[i][j] << " " ;

         }

         cout << endl;

     }*/

     bfs();

     return ;

 }