#include<iostream>
#include<algorithm>
using namespace std;
int n,a[15][15],f[15][15],ans;
signed main()
{
cin>>n;
for(int i = 1;i<=n;i++)
{
for(int j = 1;j<=i;j++)
{
cin>>a[i][j];
}
}
f[1][1] = a[1][1];
for(int i = 1;i<=n;i++)
{
for(int j = 1;j<=i;j++)
{
f[i][j] = max((f[i-1][j-1]+a[i][j]),(f[i-1][j]+a[i][j]));
ans = max(ans,f[i][j]);
}