A11960. One Occurrence

You are given an array $a$ consisting of $n$ integers, and $q$ queries to it. $i$ -th query is denoted by two integers $l_i$ and $r_i$ . For each query, you have to find any integer that occurs exactly once in the subarray of $a$ from index $l_i$ to index $r_i$ (a subarray is a contiguous subsegment of an array). For example, if $a = [1, 1, 2, 3, 2, 4]$ , then for query $(l_i = 2, r_i = 6)$ the subarray we are interested in is $[1, 2, 3, 2, 4]$ , and possible answers are $1$ , $3$ and $4$ ; for query $(l_i = 1, r_i = 2)$ the subarray we are interested in is $[1, 1]$ , and there is no such element that occurs exactly once.

Can you answer all of the queries?

The first line contains one integer $n$ ( $1 \le n \le 5 \cdot 10^5$ ).

The second line contains $n$ integers $a_1, a_2, \dots, a_n$ ( $1 \le a_i \le 5 \cdot 10^5$ ).

The third line contains one integer $q$ ( $1 \le q \le 5 \cdot 10^5$ ).

Then $q$ lines follow, $i$ -th line containing two integers $l_i$ and $r_i$ representing $i$ -th query ( $1 \le l_i \le r_i \le n$ ).

Answer the queries as follows:

If there is no integer such that it occurs in the subarray from index $l_i$ to index $r_i$ exactly once, print $0$ . Otherwise print any such integer.