求助！！！71分WA

#include<bits/stdc++.h>
using namespace std;
int head=0,tail=1;
int go[410][410];
int farm_use[410][410];
int farm_time[410][410];
int wei_x[4]={0,0,1,-1};
int wei_y[4]={-1,1,0,0};
struct stone{
    int x,y,time;
}stone[50010];
struct queue{
    int x,y;
}que[410*410];
int main(){
    int input;
    cin>>input;
    for(int i=0;i<=310;i++){
        for(int j=0;j<=310;j++){
            farm_time[i][j]=1000000000;
        }
    }
    for(int i=1;i<=input;i++){
        cin>>stone[i].x>>stone[i].y>>stone[i].time;
        farm_time[stone[i].x][stone[i].y]=stone[i].time;
        for(int j=0;j<4;j++){
            farm_time[stone[i].x+wei_x[j]][stone[i].y+wei_y[j]]=min(stone[i].time,farm_time[stone[i].x+wei_x[j]][stone[i].y+wei_y[j]]);
        }
    }
//  for(int i=0;i<=10;i++){
//      for(int j=0;j<=10;j++){
//          if(farm_time[i][j]==10) cout<<farm_time[i][j]<<" ";
//          else cout<<farm_time[i][j]<<"  ";
//      }
//      cout<<endl;
//  }
    que[1].x=0;
    que[1].y=0;
    go[que[1].x][que[1].y]=0;
    while(head<tail){
        if(farm_time[que[head].x][que[head].y]==1000000000){
            int go_now=go[que[head].x][que[head].y];
            cout<<go_now;
            return 0;
        }
        head++;
        int go_now=go[que[head].x][que[head].y]+1;
        for(int i=0;i<4;i++){
            int x_now=que[head].x+wei_x[i];
            int y_now=que[head].y+wei_y[i];
            if(x_now>=0&&y_now>=0
            &&farm_time[x_now][y_now]>go_now
            &&farm_use[x_now][y_now]==0){
                farm_use[x_now][y_now]=1;
                tail++;
                que[tail].x=x_now;
                que[tail].y=y_now;
                go[x_now][y_now]=go_now;
            }
        }
    }
    cout<<-1;
    return 0;
}