// codevs1043#include<algorithm>#include<iostream>#include<cstring>#include<cstdlib>#include<cstdio>#include<cmath>#include<queue>#define LL long long#define inf 2147483640#define MOD 10000#define Pi acos(-1.0)#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);using namespace std; const int maxn=20;int a[maxn][maxn],f[maxn][maxn][maxn][maxn],n,m;int main() {	scanf("%d",&n);	int u,v,w;	while (scanf("%d",&u)!=EOF && u) {		scanf("%d%d",&v,&w);		a[u][v]=w;	}	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++) {					f[i][j][k][l]=max(max(f[i-1][j][k-1][l],f[i-1][j][k][l-1]),max(f[i][j-1][k-1][l],f[i][j-1][k][l-1]))+a[i][j]+a[k][l];					if (i==k && j==l) f[i][j][k][l]-=a[i][j];				}	printf("%d",f[n][n][n][n]);	return 0;}