#描述#
Consider the number triangle shown below. Write a program that calculates the highest sum of numbers that can be 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.

7

3 8

8 1 0

2 7 4 4

4 5 2 6 5

In the sample above, the route from 7 to 3 to 8 to 7 to 5 produces the highest sum: 30.

#格式#
##输入格式##
Their are more than one cases.
Each case like follows.
The first line contains R (1 &lt= R &lt= 1000),R=0 means the end, the number of rows. Each subsequent line contains the integers for that particular row of the triangle. All the supplied integers are non-negative and no larger than 100.

##输出格式##
A single line containing the largest sum using the traversal specified.

#样例1#
##样例输入1##

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

##样例输出1##

30

#限制#
1000ms
32768KB

#提示#

#来源#