Not Equal on a Segment

Description:

Input:

The first line contains two integers n, m (1 ≤ n, m ≤ 2·10⁵) — the number of elements in a and the number of queries.

The second line contains n integers a_i (1 ≤ a_i ≤ 10⁶) — the elements of the array a.

Each of the next m lines contains three integers l_i, r_i, x_i (1 ≤ l_i ≤ r_i ≤ n, 1 ≤ x_i ≤ 10⁶) — the parameters of the i-th query.

Output:

Print m lines. On the i-th line print integer p_i — the position of any number not equal to x_i in segment [l_i, r_i] or the value  - 1 if there is no such number.

Sample Input:

6 4
1 2 1 1 3 5
1 4 1
2 6 2
3 4 1
3 4 2

Sample Output:

2
6
-1
4