#include<iostream>
#include<cstdio>
#define syy myson
using namespace std;
int n,x=1,y=1,z=1,a[11][11],sum[11][11][11][11],i,j,k,l;
inline int max(int a,int b)
{
	return a>b?a:b;
}
inline void input()
{
	scanf("%d",&n);
	while(x!=0&&y!=0&&z!=0)
	{
		scanf("%d%d%d",&x,&y,&z);
		a[x][y]=z;
	}
}
inline void work()
{
	for(i=1;i<=n;i++)
	  for(j=1;j<=n;j++)
	    for(k=1;k<=n;k++)
	      for(l=1;l<=n;l++)
	      {
	      	if(i==k&&j==l)
			  sum[i][j][k][l]=max(sum[i][j][k][l],max(max(max(sum[i-1][j][k-1][l],sum[i-1][j][k][l-1]),sum[i][j-1][k-1][l]),sum[i][j-1][k][l-1])+a[i][j]);
	      	else 
			  sum[i][j][k][l]=max(sum[i][j][k][l],max(max(max(sum[i-1][j][k-1][l],sum[i-1][j][k][l-1]),sum[i][j-1][k-1][l]),sum[i][j-1][k][l-1])+a[i][j]+a[k][l]);
		  }
	printf("%d",sum[n][n][n][n]);
}
int Main()
{
	freopen("fgqs.in","r",stdin);freopen("fgqs.out","w",stdout);
	input();
	work();
	return 0;
}
int main(){;};
int syy=Main();