import java.io.BufferedReader;

 import java.io.IOException;

 import java.io.InputStreamReader;

 public class Main {

     private static int row;  //行数

     private static int[][] arr;

     public static void main(String[] args) throws NumberFormatException, IOException {

         BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

         row = Integer.parseInt(br.readLine());

         arr = new int[row][row];

         for(int i = 0; i < row; i++){

             String[] str = br.readLine().split(" ");

             for(int j = 0; j <= i; j++){

                 arr[i][j] = Integer.parseInt(str[j]);

             }

         }

         int maxSum = maxSum(row,arr);

         System.out.println(maxSum);

     }

     /**

      * 最大和

      * @param row  行数

      * @param arr  数组

      * @return     该路径的最大和

      */

     private static int maxSum(int row, int[][] arr) {

         for(int i = row-2; i >= 0; i--){

             for(int j = 0; j <= i; j++){

                 arr[i][j] += maxNum(arr[i+1][j] , arr[i+1][j+1]);

             }

         }

         return arr[0][0];

     }

     /**

      * 求两个数中的最大数

      * @param a

      * @param b

      * @return    最大数

      */

     private static int maxNum(int a, int b) {

         return a>b?a:b;

     }

 }