One Occurrence

**题目大意：** 给定一个长度为 $n$ 的序列，$q$ 次询问，每次询问给定一个区间 $[l,r]$，如果这个区间里存在只出现一次的数，输出这个数（如果有多个就输出任意一个），没有就输出 $0$。 $1 \le n,q \le 5\times 10^5$。 **输入格式：** 第一行一个整数 $n$。 接下来 $1$ 行 $n$ 个小于 $5\times 10^5$ 的正整数表示给出的序列。 下面一行一个整数 $m$。 再下面 $m$ 行，每行两个整数 $l,r$，表示一次询问。 **输入格式：** 共 $m$ 行，每行输出对应的答案。 感谢@守望 提供翻译

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.

6
1 1 2 3 2 4
2
2 6
1 2

4
0