#include <iostream>
#include <algorithm>
using namespace std;
const int N = 1e3 + 10; 
int a[N][N];
int main(){
	int n;
	cin >> n;
	for(int i = 1; i <= n; i++){
		for(int j = 1; j <= i; j++){
			cin >> a[i][j];
		}
	}
	for(int i = 1; i <= n; i++){
		for(int j = 1; j <= i; j++){
			a[i][j] = max(a[i-1][j-1], a[i-1][j]) + a[i][j];
		}
	}
	int maxx = 0;
	for(int i = 1; i <= n; i++){
		maxx = max(maxx, a[n][i]);
	}
	cout << maxx << endl;
}