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 nn positive integers, a1,a2,...,ana_{1},a_{2},...,a_{n} .

First Sereja took a piece of squared paper and wrote all distinct non-empty non-decreasing subsequences of sequence aa . 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,...,xrx=x_{1},x_{2},...,x_{r} doesn't exceed a sequence of positive integers y=y1,y2,...,yry=y_{1},y_{2},...,y_{r} , if the following inequation holds: x1<=y1,x2<=y2,...,xr<=yrx_{1}<=y_{1},x_{2}<=y_{2},...,x_{r}<=y_{r} .

Now Sereja wonders, how many sequences are written on the lines piece of paper. Help Sereja, find the required quantity modulo 10000000071000000007 (109+7)(10^{9}+7) .

输入格式

The first line contains integer nn (1<=n<=105)(1<=n<=10^{5}) . The second line contains nn integers a1,a2,...,ana_{1},a_{2},...,a_{n} (1<=ai<=106)(1<=a_{i}<=10^{6}) .

输出格式

In the single line print the answer to the problem modulo 10000000071000000007 (109+7)(10^{9}+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
    
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