#include<cstdio>
#include<iostream>
#include<cmath>
using namespace std;
int n,a,b,c,jz[11][11],f[11][11][11][11];
int main()
{
	freopen("fgqs.in","r",stdin);
	freopen("fgqs.out","w",stdout);
	scanf("%d%d%d%d",&n,&a,&b,&c);
	while(a!=0&&b!=0&&c!=0)
	{
		jz[a][b]=c;
		scanf("%d%d%d",&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 l=1;l<=n;l++)
	      {
	      	int suma=max(f[i-1][j][k-1][l],f[i][j-1][k][l-1]);
	      	int sumb=max(f[i-1][j][k][l-1],f[i][j-1][k-1][l]);
	      	f[i][j][k][l]=max(suma,sumb)+jz[i][j];
	      	if(i!=k&&j!=l)f[i][j][k][l]+=jz[k][l];
		  }
	printf("%d",f[n][n][n][n]);
	return 0;
}