#include<bits/stdc++.h>
using namespace std;
int n,a[15][15],dp[15][15][15][15] ,w1,w2,zhi;
int main(){
	cin>>n;
	while(cin>>w1>>w2>>zhi&&w1!=0&&w2!=0&&zhi!=0){		
		a[w1][w2]=zhi; 
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++){
			for(int k=1;k<=n;k++){
				for(int l=1;l<=n;l++){
					//dp[i - 1][j][l - 1][k]
					//dp[i][j - 1][l][k-1]
					//dp[i - 1][j][l][k - 1]
					//dp[i][j - 1][l - 1][k] 
					dp[i][j][k][l]= max(max(dp[i - 1][j][l - 1][k],dp[i][j - 1][l][k-1]),max(dp[i - 1][j][l][k - 1],dp[i][j - 1][l - 1][k] ))+ a[i][j];             
					if(i != 1 && j != l) dp[i][j][k][l] += a[l][k];
				}
			}
		} 
	}
	cout<<dp[n][n][n][n];
	return 0;
}

58分

https://www.luogu.com.cn/record/200013965