import java.util.*;

public class Main {
    static final int N = 12;
    static int[][] g = new int[N][N];
    static int[][][] f = new int[2 * N][N][N];
    static int n;

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        n = Integer.parseInt(sc.nextLine());

        while (true) {
            String[] s = sc.nextLine().split(" ");
            int x = Integer.parseInt(s[0]), y = Integer.parseInt(s[1]), c = Integer.parseInt(s[2]);
            if (x == 0) break;
            g[x][y] = c;
        }

        int ans = dp();

        System.out.println(ans);
    }

    static int dp() {
        int[] dx = {-1, 0, -1, 0}, dy = {-1, -1, 0, 0};
        for (int k = 2; k <= 2 * n; k++) 
            for (int i1 = 1; i1 <= n; i1++)
                for (int i2 = 1; i2 <= n; i2++) {
                    int j1 = k - i1, j2 = k - i2;
                    if (j1 >= 1 && j1 <= n && j2 >= 1 && j2 <= n) {
                        int t = g[i1][j1];
                        if (i1 != i2) t += g[i2][j2];
                        for (int i = 0; i < 4; i++) {
                            int x = i1 + dx[i], y = i2 + dy[i];
                            f[k][i1][i2] = Math.max(f[k][i1][i2], f[k - 1][x][y] + t);
                        }
                    }
                }

        return f[2 * n][n][n];
    }
}