#P11002. [2016杭电多校]Shell Necklace
[2016杭电多校]Shell Necklace
Shell Necklace
Problem Description
Perhaps the sea‘s definition of a shell is the pearl. However, in my view, a shell necklace with n beautiful shells contains the most sincere feeling for my best lover Arrietty, but even that is not enough. Suppose the shell necklace is a sequence of shells (not a chain end to end). Considering i continuous shells in the shell necklace, I know that there exist different schemes to decorate the i shells together with one declaration of love. I want to decorate all the shells with some declarations of love and decorate each shell just one time. As a problem, I want to know the total number of schemes.
Input
There are multiple test cases(no more than cases and no more than 1 in extreme case), ended by 0. For each test cases, the first line contains an integer , meaning the number of shells in this shell necklace, where . Following line is a sequence with non-negative integer , and meaning the number of schemes to decorate continuous shells together with a declaration of love.
Output
For each test case, print one line containing the total number of schemes module (Three hundred and thirteen implies the march 13th, a special and purposeful day).
Sample Input
3
1 3 7
4
2 2 2 2
0
Sample Output
14
54
Hint
For the first test case in Sample Input, the Figure 1 provides all schemes about it. The total number of schemes is 1 + 3 + 3 + 7 = 14.
Author
HIT
Source
2016 Multi-University Training Contest 1