CF314C.Sereja and Subsequences
普及/提高-
通过率:0%
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题目描述
Sereja has a sequence that consists of n positive integers, a1,a2,...,an .
First Sereja took a piece of squared paper and wrote all distinct non-empty non-decreasing subsequences of sequence a . Then for each sequence written on the squared paper, Sereja wrote on a piece of lines paper all sequences that do not exceed it.
A sequence of positive integers x=x1,x2,...,xr doesn't exceed a sequence of positive integers y=y1,y2,...,yr , if the following inequation holds: x1<=y1,x2<=y2,...,xr<=yr .
Now Sereja wonders, how many sequences are written on the lines piece of paper. Help Sereja, find the required quantity modulo 1000000007 (109+7) .
输入格式
The first line contains integer n (1<=n<=105) . The second line contains n integers a1,a2,...,an (1<=ai<=106) .
输出格式
In the single line print the answer to the problem modulo 1000000007 (109+7) .
输入输出样例
输入#1
1 42
输出#1
42
输入#2
3 1 2 2
输出#2
13
输入#3
5 1 2 3 4 5
输出#3
719