#include <bits/stdc++.h>
#include<algorithm>
using namespace std;
#define MAX 101
int D[MAX][MAX];
int n;int *maxSum;
int main(){
int i,j;
cin>>n;
for(i=1;i<=n;i++)
for(j=1;j<=i;j++)
cin>>D[i][j];
maxSum=D[n];//maxSum point at di n hang
for(int i=n-1;i>=1;i--)
for(int j=1;j<=i;++j)
maxSum[j]=
max(maxSum[j],maxSum[j+1])+D[i][j];
cout<<maxSum[1]<<endl;
}
