package quki.algorithm.dp;

import java.util.Scanner;

public class BOJ1932 {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

int n = sc.nextInt();

int a[][] = new int[n + 1][n + 1];

int d[][] = new int[n + 1][n + 1];

for (int i = 1; i <= n; i++) {

for (int j = 1; j <= i; j++) {

a[i][j] = sc.nextInt();

}

}

d[1][1] = a[1][1];

for (int i = 2; i <= n; i++) {

for (int j = 1; j <= i; j++) {

d[i][j] = Math.max(d[i-1][j-1], d[i-1][j]) +a[i][j];

}

}

int sum = -1;

for(int i = 1; i<=n;i++){

sum = Math.max(d[n][i], sum);

}

System.out.println(sum);

}

}