#include <iostream>
#include<string.h>
using namespace std;
int a[1005][1005],b[1005][1005];
int n;
int max(int x, int y)
{ return x>y?x:y ; }

int f(int i,int j)
{
if(b[i][j]!=-1) return b[i][j];
return b[i][j]=a[i][j]+max(f(i+1,j),f(i+1,j+1));
}

int main()
{
int i,j;

while(cin>>n)
{

for(i=0;i<n;i++)
for(j=0;j<=i;j++) cin>>a[i][j];
memset(b,-1,sizeof(b));
for(j=0;j<n;j++) b[i-1][j]=a[i-1][j];
cout<<f(0,0)<<endl;
}

}