#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
int n, q;
int in[300010];
vector<pii> query[300010];
int ans[300010], out[300010];
struct BITree {
  int num[300010];
  BITree() { memset(num, 0, sizeof(num)); }
  void add(int x, int y) {
    while (x <= n) {
      num[x] += y;
      x += x & -x;
    }
  }
  int query(int x) {
    int re = 0;
    while (x) {
      re += num[x];
      x -= x & -x;
    }
    return re;
  }
} bit;
int find(int now) {
  int all = ans[now];
  int fn = in[now];
  int l = 0, r = now;
  while (l + 1 < r) {
    int m = (l + r) / 2;
    if (all - bit.query(m) >= fn)
      l = m;
    else
      r = m;
  }
  return l;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> q;
  for (int i = 1; i <= n; i++) {
    cin >> in[i];
    in[i] = i - in[i];
  }
  for (int i = 0; i < q; i++) {
    int a, b;
    cin >> a >> b;
    query[n - b].emplace_back(pii(a, i));
  }
  for (int i = 1; i <= n; i++) {
    ans[i] = ans[i - 1];
    if (in[i] >= 0 && ans[i - 1] >= in[i]) {
      int last = find(i);
      bit.add(last + 1, 1);
      ans[i]++;
    }
    for (pii &x : query[i]) out[x.second] = ans[i] - bit.query(x.first);
  }
  for (int i = 0; i < q; i++) cout << out[i] << '\n';
  return 0;
}
