#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
int a[11][11],b[11][11][11][11];
int main()
{
	freopen("fgqs.in","r",stdin);
	freopen("fgqs.out","w",stdout);
	int n,x,y,z,s,f;
	cin>>n>>x>>y>>z;
	while(x&&y&&z)
	{
		a[x][y]=z;
		cin>>x>>y>>z;
	}
	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++)
	{
	//	s=;
	//	k=;
		b[i][j][k][l]=max(max(b[i-1][j][k-1][l],b[i][j-1][k][l-1]),max(b[i-1][j][k][l-1],b[i][j-1][k-1][l]))+a[i][j];
		if(i!=k&&j!=l) b[i][j][k][l]+=a[k][l];
		
	}
	cout<<b[n][n][n][n];
	return 0;
}