#5845. Distinct Values Subsequences
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Distinct Values Subsequences
Distinct Values Subsequences
Given an array of n integers, count the number of subsequences where each element is distinct. A subsequence is a sequence of array elements from left to right that may have gaps.
Input
The first line has an integer n: the array size. The second line has n integers x_1,x_2,\dots,x_n: the array contents.
Output
Print the number of subsequences with distinct elements. The answer can be large, so print it modulo 10^9+7.
Constraints
\cdot 10^5$
Example
Input
4
1 2 1 3
Output
11
Explanation: The subsequences are [1] (two times), [2], [3], [1,2], [1,3] (two times), [2,1], [2,3], [1,2,3] and [2,1,3].