#include <bits/stdc++.h>
using namespace std;
const int maxn = 5e5 + 60;
struct Tree {
  int val[maxn];
  int N;
  inline int lowbit(int x) { return x & (-x); }
  void init(int n) {
    N = n;
    for (int i = 1; i <= n; i++) {
      val[i] = 0;
    }
  }
  void add(int pos, int v) {
    while (pos > 0) {
      val[pos] += v;
      pos -= lowbit(pos);
    }
  }
  int sum(int pos) {
    int res = 0;
    while (pos <= N) {
      res += val[pos];
      pos += lowbit(pos);
    }
    return res;
  }
} T;
int saveori[maxn];
int saveans[maxn];
struct node {
  int l, r;
  int id;
  bool operator<(const node &n) const {
    if (r != n.r) {
      return r < n.r;
    } else {
      return l < n.l;
    }
  }
} saveq[maxn];
int n, q;
int cjladd(int x, int r) {
  int l = 1;
  int pos = -1;
  while (l <= r) {
    int mid = l + r;
    mid /= 2;
    if (T.sum(mid) >= x) {
      pos = mid;
      l = mid + 1;
    } else {
      r = mid - 1;
    }
  }
  return pos;
}
void solve() {
  cin >> n >> q;
  T.init(n + 10);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &saveori[i]);
    saveori[i] = i - saveori[i];
  }
  for (int i = 1; i <= q; i++) {
    int x, y;
    scanf("%d %d", &x, &y);
    saveq[i].l = 1 + x;
    saveq[i].r = n - y;
    saveq[i].id = i;
  }
  sort(saveq + 1, saveq + 1 + q);
  int nowrarr = 1;
  for (int i = 1; i <= q; i++) {
    node nownode = saveq[i];
    while (nowrarr <= nownode.r) {
      if (saveori[nowrarr] == 0) {
        T.add(nowrarr, 1);
        nowrarr++;
      } else if (saveori[nowrarr] < 0) {
        nowrarr++;
        continue;
      } else {
        int d = cjladd(saveori[nowrarr], nowrarr);
        if (d != -1) {
          T.add(d, 1);
        }
        nowrarr++;
      }
    }
    saveans[nownode.id] = T.sum(nownode.l);
  }
  for (int i = 1; i <= q; i++) {
    cout << saveans[i] << endl;
  }
}
int main() { solve(); }
