#include <iostream> 
#include <algorithm> 
#define MAX 200
using namespace std; 
int D[MAX][MAX];
int n;
int MaxSum(int i, int j)
{
	if(i == n)
		return D[i][j];
	int x = MaxSum(i + 1,j); 
	int y = MaxSum(i + 1,j+1); 
		return max(x,y) + D[i][j];
}
int main()
{
	int i,j;
	cin >> n; 
	for(i = 1;i <= n;i++)
		for(j = 1;j <= i;j++)
			cin >> D[i][j];
	cout << MaxSum(1,1) << endl;
} 

RT，有RE也有TEL /kk