B. Little Elephant and Array
time limit per test
4 seconds
memory limit per test
256 megabytes
standard input
standard output

The Little Elephant loves playing with arrays. He has array a, consisting of n positive integers, indexed from 1 to n. Let's denote the number with index i as a i.

Additionally the Little Elephant has m queries to the array, each query is characterised by a pair of integers l j and r j (1 ≤ l j ≤ r j ≤ n). For each query l j, r j the Little Elephant has to count, how many numbers x exist, such that number x occurs exactly x times among numbers a l j, a l j + 1, ..., a r j.

Help the Little Elephant to count the answers to all queries.


The first line contains two space-separated integers n and m (1 ≤ n, m ≤ 105) — the size of array a and the number of queries to it. The next line contains n space-separated positive integers a 1, a 2, ..., a n (1 ≤ a i ≤ 109). Next m lines contain descriptions of queries, one per line. The j-th of these lines contains the description of the j-th query as two space-separated integers l j and r j (1 ≤ l j ≤ r j ≤ n).


In m lines print m integers — the answers to the queries. The j-th line should contain the answer to the j-th query.

7 2
3 1 2 2 3 3 7
1 7
3 4