#include <bits/stdc++.h>

using namespace std;

const int CMAX = 105;
int a[CMAX][CMAX] , n , maxim;
long b[CMAX][CMAX];

int triunghi(int a[][CMAX],long b[][CMAX])
{
    for(int i=1;i<=n;i++)
    {
        b[i][0] = 0;
    }
    b[1][1] = a[1][1];
    for(int i=2;i<=n;i++)
    {
        for(int j=1;j<=i;j++)
        {
            maxim = b[i-1][j];
            if(b[i-1][j-1]>maxim)maxim = b[i-1][j-1];
            b[i][j] = maxim + a[i][j];
        }
    }
    maxim = b[n][1];
    for(int i=2;i<=n;i++)
    {
        if(maxim<b[n][i])maxim = b[n][i];
    }
    return maxim;
}

int main()
{
    ifstream fin("sumtri.in");
    fin >> n;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=i;j++)
        {
            fin >> a[i][j];
        }
    }
    fin.close();
    ofstream fout("sumtri.out");
    fout << triunghi(a,b);
    fout.close();
    return 0;
}