The Triangle
时间限制：C/C++/Rust/Pascal 1秒，其他语言2秒
空间限制：C/C++/Rust/Pascal 9.765625 M，其他语言19.53125 M
64bit IO Format: %lld

题目描述 

7
3   8
8   1   0
2   7   4   4
4   5   2   6   5

(Figure 1)
Figure 1 shows a number triangle. Write a program that calculates the highest sum of numbers passed on a route that starts at the top and ends somewhere on the base. Each step can go either diagonally down to the left or diagonally down to the right.

输入描述:

Your program is to read from standard input. The first line contains one integer N: the number of rows in the triangle. The following N lines describe the data of the triangle. The number of rows in the triangle is > 1 but <= 100. The numbers in the triangle, all integers, are between 0 and 99.

输出描述:

Your program is to write to standard output. The highest sum is written as an integer.
示例1

输入

复制 
5
7
3 8
8 1 0 
2 7 4 4
4 5 2 6 5

输出

复制 
30