#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>

using namespace std;

const int N = 10;

int g[N][N];
int f[N][N][N][N];

int main()
{
    int n;
    cin >> n;

    for( ; ; )
    {
        int x, y, z;
        cin >> x >> y >> z;
        if(x == 0 && y == 0 && z == 0)
        {
            break;
        }
        else
        {
            g[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 o = 1; o <= n; o ++ )
                {
                    f[i][j][k][o] = max(max(f[i - 1][j][k - 1][o], f[i - 1][j][k][o - 1]), max(f[i][j - 1][k - 1][o], f[i][j - 1][k][o - 1])) + g[i][j] + g[k][o];
                    if(i == k && j == o)
                    {
                        f[i][j][k][o] -= g[i][j];
                    }
                }
            }
        }
    }

    cout << f[n][n][n][n] << endl;

    return 0;
}