#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
int f[11][11][11][11];
int a[11][11];
int n;
inline int max(int b,int c,int d,int e)
{
	int s;
	if(b>c) s=b;
	else s=c;
	if(d>s) s=d;
	if(e>s) s=e;
	return s;
}
int Main()
{
	freopen("fgqs.in","r",stdin);
	freopen("fgqs.out","w",stdout);
	scanf("%d",&n);
	int A,B,C;
	for(int i=1;i<=10000;i++)
	{
		scanf("%d%d%d",&A,&B,&C);
		if(A==0&&B==0&&C==0)
			break;
		else
			a[A][B]=C;
	}
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
			for(int k=1;k<=n;k++)
				for(int p=1;p<=n;p++)
				{
					f[i][j][k][p]=max(f[i-1][j][k-1][p],f[i-1][j][k][p-1],f[i][j-1][k-1][p],f[i][j-1][k][p-1])+a[i][j];
					if(i!=k||j!=p)
					f[i][j][k][p]+=a[k][p];
				}
	printf("%d",f[n][n][n][n]);
	fclose(stdin);
	fclose(stdout);
	return 0;
}
int work=Main();
int main(){;}