#include<stdio.h>
int book[310][310], book1[310][310], book2[310][310], nest[4][2] = { {0,1},{1,0},{-1,0},{0,-1} };
struct nb {
	int x;
	int y;
	int s;
} a[90020];
int main()
{
	int n, i, j;
	scanf("%d", &n);
	memset(book1, 100, sizeof(book1));
	for (i = 1; i <= n; i++)
	{
		int g, k, h;
		scanf("%d %d %d", &g,&k,&h);
		if (book1[g][k] > h);
			book1[g][k] = h;
		book2[g][k] = 1;
		for (j = 0; j <= 3; j++)
		{
			int tx = g + nest[j][0];
			int ty = k + nest[j][1];
			if (tx < 0 || tx>300 || ty < 0 || ty>300)
				continue;
			if (book1[tx][ty] > h)
				book1[tx][ty] = h;
			book2[tx][ty] = 1;
		}
	}
	if (book2[0][0] == 0)
	{
		printf("0\n");
		return 0;
	}
	int hard = 1, tail = 1;
	a[tail].x = 0;
	a[tail].y = 0;
	a[tail].s = 0;
	book[0][0] = 1;
	tail++;
	int flag = 0;
	while (hard < tail)
	{
		for (i = 0; i <= 3; i++)
		{
			int tx = a[hard].x + nest[i][0];
			int ty = a[hard].y + nest[i][1];
			if (tx < 0 || tx>300 || ty < 0 || ty>300)
				continue;
			if (a[hard].s + 1 >= book1[tx][ty])
				continue;
			if (book[tx][ty] == 0)
			{
				a[tail].x = tx;
				a[tail].y = ty;
				a[tail].s = a[hard].s + 1;
				book[tx][ty] = 1;
				tail++;
			}
			if (book2[tx][ty] == 0)
			{
				flag = 1;
				break;
			}
		}
		if (flag == 1)
		{
			break;
		}
		hard++;
	}
	if (flag == 1)
		printf("%d\n", a[tail - 1].s);
	else
		printf("-1\n");
	return 0;
}