AT_abc390_f [ABC390F] Double Sum 3
Description
You are given an integer sequence $ A=(A_1,A_2,\ldots,A_N) $ of length $ N $ .
For each integer pair $ (L,R) $ with $ 1 \le L \le R \le N $ , define $ f(L,R) $ as follows:
- Start with an empty blackboard. Write the $ R-L+1 $ integers $ A_L, A_{L+1}, \ldots, A_R $ on the blackboard in order.
- Repeat the following operation until all integers on the blackboard are erased:
- Choose integers $ l, r $ with $ l \le r $ such that every integer from $ l $ through $ r $ appears at least once on the blackboard. Then, erase all integers from $ l $ through $ r $ that are on the blackboard.
- Let $ f(L,R) $ be the minimum number of such operations needed to erase all the integers from the blackboard.
Find $ \displaystyle \sum_{L=1}^N \sum_{R=L}^N f(L,R) $ .
Input Format
The input is given from Standard Input in the following format:
> $ N $ $ A_1 $ $ A_2 $ $ \ldots $ $ A_N $
Output Format
Print the answer.
Explanation/Hint
### Sample Explanation 1
For example, in the case of $ (L,R)=(1,4) $ :
- The blackboard has $ 1,3,1,4 $ .
- Choose $ (l,r)=(1,1) $ and erase all occurrences of $ 1 $ . The blackboard now has $ 3,4 $ .
- Choose $ (l,r)=(3,4) $ and erase all occurrences of $ 3 $ and $ 4 $ . The blackboard becomes empty.
- It cannot be done in fewer than two operations, so $ f(1,4) = 2 $ .
Similarly, you can find $ f(2,4)=2 $ , $ f(1,1)=1 $ , etc.
$ \displaystyle \sum_{L=1}^N \sum_{R=L}^N f(L,R) = 16 $ , so print $ 16 $ .
### Constraints
- $ 1 \le N \le 3 \times 10^5 $
- $ 1 \le A_i \le N $
- All input values are integers.