#include<iostream>
#include<cstdio>
using namespace std;
int n,a,b,c;
int s[11][11],dp[11][11][11][11];
int main(){
	freopen("fgqs.in","r",stdin);
	freopen("fgqs.out","w",stdout);
	cin>>n>>a>>b>>c;
	while(a&&b&&c){
		s[a][b]=c;
		cin>>a>>b>>c;
	}
	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++){
		dp[i][j][k][l]=max(max(dp[i-1][j][k-1][l],dp[i][j-1][k][l-1]),max(dp[i][j-1][k-1][l],dp[i-1][j][k][l-1]))+s[i][j]+s[k][l];
		if(i==k&&j==l)dp[i][j][k][l]-=s[k][l];
	}
	cout<<dp[n][n][n][n];
	fclose(stdin);
	fclose(stdout);
	return 0;
}