#include<bits/stdc++.h>
using namespace std;
int n;
int x,y,num;
int d[10][10];
int f[10][10][10];
int main(){
	scanf("%d",&n);
	while(scanf("%d%d%d",&x,&y,&num)&&x!=0&&y!=0&&num!=0){
		d[x][y]=num;
	}
	for (int i=1;i<=n;i++){
		for (int j=1;j<=n;j++){
			for (int k=1;k<=n;k++){
				f[i][j][k]=max(max(f[i-1][j][k-1],f[i-1][j][k]),max(f[i][j-1][k-1],f[i][j-1][k]))+d[i][j];
				if(i!=k){
					f[i][j][k]+=d[k][i+j-k];
				}
			}
		}
	}
	printf("%d",f[n][n][n]);
}