#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int main()
{
	int a[105][105];
	int n,x;
	while(scanf("%d",&n)!=EOF)
	{
		int big=0;
		memset(a,0,sizeof(a));
		for(int i=1;i<=n;i++)
			for(int j=1;j<=i;j++)
			{
				cin>>x;
				a[i][j]=max(a[i-1][j-1]+x,a[i-1][j]+x);
			}
		for(int i=1;i<=n;i++)
			if(a[n][i]>big) big=a[n][i];
		cout<<big<<endl;
	}
	return 0;
}