#include<bits/stdc++.h>
using namespace std;
int n,a[11][11],x,y,s1=0,s2=0,s=0;
int f(int x1,int y1)
{
	if(x1>n&&y1>n){
		if(s>s1) s2=s1,s1=s;
		if(s>s2) s2=s;
		s=0;
	}
	if(x1<=n) 
	{
		s+=a[x1][y1];
		f(x1+1,y1);
	}
	if(y1<=n)
	{
		s+=a[x1][y1];
		f(x1,y1+1);
	}
}
int main(){
	cin>>n;
	for(;;)
	{
		cin>>x>>y;
		if(x==0&&y==0)	break;
		else cin>>a[x][y];
	}
	f(0,0);
	cout<<s1+s2;
	return 0;
}