include[HTML_REMOVED]
using namespace std;
int maze[600][600];
int main()
{
int n;cin>>n;
for(int i=1;i<=n;i)
for(int j=1;j<=i;j)
cin>>maze[i][j];
for(int i=n-1;i>=1;i–)
{
for(int j=1;j<=i;j++)
maze[i][j]=max(maze[i][j]+maze[i+1][j],maze[i][j]+maze[i+1][j+1]);
}
cout<<maze[1][1];
}