rt，蒟蒻代码如下：

#include <iostream>
#include <cstdio>
#include <queue>
#include <cmath>
#define stn frm[x+trn[i][0]+1][y+trn[i][1]+1]
#define nxtx x.x+trn[i][0]
#define nxty x.y+trn[i][1]
using namespace std;

int m, x, y, t, frm[303][303];
int trn[5][2] = {0,0,-1,0,1,0,0,-1,0,1};
struct pos{
	int x, y, t;
} stt;
queue<pos> q;

int bfs(pos x){
	if(frm[x.x][x.y]==50001)	return x.t-1;					
	frm[x.x][x.y] = -1;
	for(int i=1; i<5; ++i){
		if(frm[nxtx][nxty]<=x.t)	continue;
		if(nxtx<1 || nxtx>301 || nxty<1 || nxty>301)	continue;
		pos y{nxtx, nxty, x.t+1};	
		q.push(y);
	}
	if(q.size()==0)	return -1;
	pos y = q.front();	q.pop();
	return bfs(y);		
}

int main(){
	for(int i=1; i<302; ++i)
		for(int j=1; j<302; ++j)
			frm[i][j] = 50001;
	scanf("%d", &m);
	while(m--){
		scanf("%d%d%d", &x,&y,&t);
		for(int i=0; i<5; ++i)	stn = min(stn, t);
	}
	stt.x = stt.y = stt.t = 1;
	printf("%d", bfs(stt));
	return 0;
}