#include <iostream>
#include <cstdio>
using namespace std;
int A[15][15]={0},n,x,y,gg,max_,f[15][15][15][15];
int main()
{
	freopen("fgqs.in","r",stdin);
	freopen("fgqs.out","w",stdout);
	scanf("%d",&n);
	for(;;)
	{
		scanf("%d%d%d",&x,&y,&gg);
		if(x==0&&y==0&&gg==0)
		break;
		A[x][y]=gg;
	}
	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++)
				{
					max_=max(max(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]);
					f[i][j][k][p]=max_+A[i][j];
					if(i!=k||j!=p)
						f[i][j][k][p]+=A[k][p];
				}
	cout<<f[n][n][n][n]<<endl;
	return 0;
}