#include <iostream>
#include <cmath>
using namespace std;
int m;
int time=0;
int finalmap[310][310]={0},currentmap[310][310]={0};
int sequence[50010]={0};
int s=1;
int startime[50010]={0};
int starpoint[2][50010]={0};
int currentpoint[2][10000]={0};
int comingpoint[2][10000]={0};
int currentpointnum=1;
int comingpointnum=0;
int mov(int x,int y)
{
    if (finalmap[x][y]==0)
    {
        return 1;
    }
    else
    {
        if (currentmap[x][y]==0)
        {
            comingpoint[x][y]=time;
            comingpointnum++;
            comingpoint[0][comingpointnum]=x;
            comingpoint[1][comingpointnum]=y;
            return 0;
        }
        return 0;
    }
}
int main(void)
{
    finalmap[0][0]=-1;
    currentmap[0][0]=-1;
    for (int i=1;i<=309;i++)
    {
        finalmap[0][i]=-1;
        currentmap[0][i]=-1;
        finalmap[i][0]=-1;
        currentmap[i][0]=-1;
    }
    cin>>m;
    scanf("%d%d%d",&starpoint[0][1],&starpoint[1][1],&startime[1]);
    starpoint[0][1]++;
    starpoint[1][1]++;
    sequence[1]=1;
    finalmap[starpoint[0][1]][starpoint[1][1]]=-1;
    finalmap[starpoint[0][1]+1][starpoint[1][1]]=-1;
    finalmap[starpoint[0][1]-1][starpoint[1][1]]=-1;
    finalmap[starpoint[0][1]][starpoint[1][1]+1]=-1;
    finalmap[starpoint[0][1]][starpoint[1][1]-1]=-1;
    for (int i=2;i<=m;i++)
    {
        scanf("%d%d%d",&starpoint[0][i],&starpoint[1][i],&startime[i]);
        starpoint[0][i]++;
        starpoint[1][i]++;
        sequence[i]=i;
        finalmap[starpoint[0][i]][starpoint[1][i]]=-1;
        finalmap[starpoint[0][i]+1][starpoint[1][i]]=-1;
        finalmap[starpoint[0][i]-1][starpoint[1][i]]=-1;
        finalmap[starpoint[0][i]][starpoint[1][i]+1]=-1;
        finalmap[starpoint[0][i]][starpoint[1][i]-1]=-1;
        //sort
        if (startime[sequence[i]]<startime[sequence[i-1]])
        {
            if (startime[sequence[i]]<startime[sequence[1]])
            {
                for (int j=i;j>=1;j--)
                {
                    sequence[j+1]=sequence[j];
                }
                sequence[1]=i;
            }
            else
            {
                int p1=1,p2=i-1;
                while (p2-p1>1)
                {
                    if (startime[(p1+p2)/2]>startime[i])
                    {
                        p2=(p1+p2)/2;
                    }
                    else
                    {
                        p1=(p1+p2)/2;
                    }
                }
                for (int j=i;j>=p2;j--)
                {
                    sequence[j+1]=sequence[j];
                }
                sequence[p2]=i;
            }
        }
    }
    currentpoint[0][1]=1;
    currentpoint[1][1]=1;
    currentmap[1][1]=1;
    if (finalmap[1][1]==0)
    {
        cout<<'0';
        return 0;
    }
    while (currentpointnum)
    {
        time++;
        comingpointnum=0;
        while (time==startime[sequence[s]])
        {
            currentmap[starpoint[0][sequence[s]]][starpoint[1][sequence[s]]]=-1;
            currentmap[starpoint[0][sequence[s]]+1][starpoint[1][sequence[s]]]=-1;
            currentmap[starpoint[0][sequence[s]]-1][starpoint[1][sequence[s]]]=-1;
            currentmap[starpoint[0][sequence[s]]][starpoint[1][sequence[s]]+1]=-1;
            currentmap[starpoint[0][sequence[s]]][starpoint[1][sequence[s]]-1]=-1;
            s++;
        }
        for (int i=1;i<=currentpointnum;i++)
        {
            if (mov(currentpoint[0][i]+1,currentpoint[1][i]))
            {
                cout<<time;
                return 0;
            }
            if (mov(currentpoint[0][i]-1,currentpoint[1][i]))
            {
                cout<<time;
                return 0;
            }
            if (mov(currentpoint[0][i],currentpoint[1][i]+1))
            {
                cout<<time;
                return 0;
            }
            if (mov(currentpoint[0][i],currentpoint[1][i]-1))
            {
                cout<<time;
                return 0;
            }
        }
        for (int i=1;i<=comingpointnum;i++)
        {
            currentpoint[0][i]=comingpoint[0][i];
            currentpoint[1][i]=comingpoint[1][i];
        }
        currentpointnum=comingpointnum;
    }
    cout<<"-1";
    return 0;
}

做了一天了，好不容易样例过了，这样真的让我破防