#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main()
{
    int n;
    vector<vector<int> > matrix;

    cin>>n;

    for (int i = 0; i < n; i++)
    {
        vector<int> temp;
        for (int j = 0; j <= i; j++)
        {
            int in;
            cin>>in;
            temp.push_back(in);
        }
        matrix.push_back(temp);
    }

    for (int i = matrix.size() - 1; i > 0; i--)
    {
        for (int j = 0; j < matrix[i-1].size(); j++)
        {
            if (matrix[i][j] > matrix[i][j+1])
            {
                matrix[i-1][j] += matrix[i][j];
            }
            else
            {
                matrix[i-1][j] += matrix[i][j+1];
            }
        }
    }
    cout<<matrix[0][0];
    return 0;
}