#include<iostream>
#include<cstring>
using namespace std;

const int N=15;
int s[N][N];
int f[N][N][N][N];
//f[i1,j1,i2,j2]
int main()
{
    int n;
    cin>>n;

    int a,b,c;
    while(cin>>a>>b>>c,a||b||c) s[a][b]=c;

    for(int i1=1;i1<=n;i1++)
        for(int j1=1;j1<=n;j1++)
            for(int i2=1;i2<=n;i2++)
                for(int j2=1;j2<=n;j2++)
                {
                    int t=s[i1][j1];
                    if(!(i1==i2&&j1==j2))
                        t+=s[i2][j2];
                    int &x=f[i1][j1][i2][j2];
                    x=max(x,f[i1-1][j1][i2-1][j2]+t);
                    x=max(x,f[i1-1][j1][i2][j2-1]+t);
                    x=max(x,f[i1][j1-1][i2-1][j2]+t);
                    x=max(x,f[i1][j1-1][i2][j2-1]+t);
                }
    cout<<f[n][n][n][n]<<endl;
}