#include <bits/stdc++.h>
using namespace std;
const int MAXN = 300100;
const int INF = 0x3f3f3f3f;
struct seg {
  seg *fe, *fd;
  int meio, l, r, soma, lazy;
  pair<int, int> mix;
  seg(int x, int y) {
    meio = (x + y) / 2;
    l = x, r = y;
    soma = lazy = 0;
    mix = {0, l};
    if (x == y) return;
    fe = new seg(x, meio);
    fd = new seg(meio + 1, y);
  }
  void lazyup() {
    if (lazy == 0) return;
    soma += (r - l + 1) * lazy;
    mix.first += lazy;
    if (l != r) fe->lazy += lazy, fd->lazy += lazy;
    lazy = 0;
  }
  void up(int a, int b, int novo) {
    lazyup();
    if (l >= a && r <= b) {
      lazy += novo;
      lazyup();
      return;
    }
    if (l > b || r < a) return;
    fe->up(a, b, novo), fd->up(a, b, novo);
    if (fe->mix.first <= fd->mix.first)
      mix = fe->mix;
    else
      mix = fd->mix;
    soma = fe->soma + fd->soma;
  }
  pair<int, int> get(int a, int b) {
    lazyup();
    if (l >= a && r <= b) return mix;
    if (l > b || r < a) return {INF, INF};
    pair<int, int> re = fe->get(a, b), rd = fd->get(a, b);
    if (re.first <= rd.first) return re;
    return rd;
  }
  int gets(int a, int b) {
    lazyup();
    if (l >= a && r <= b) return soma;
    if (l > b || r < a) return 0;
    return fe->gets(a, b) + fd->gets(a, b);
  }
};
int v[MAXN];
int resp[MAXN];
vector<pair<int, int>> vec[MAXN];
seg st(0, MAXN);
seg sum(0, MAXN);
int main() {
  int n, q;
  cin >> n >> q;
  for (int i = 1; i <= n; i++) cin >> v[i];
  for (int i = 1; i <= q; i++) {
    int x, y;
    cin >> x >> y;
    vec[x].push_back({y, i});
  }
  for (int i = n; i >= 0; i--) {
    for (auto j : vec[i]) {
      resp[j.second] = sum.gets(i + 1, n - j.first);
    }
    if (v[i] <= i)
      st.up(i, i, i - v[i]);
    else
      st.up(i, i, INF);
    while (true) {
      pair<int, int> h = st.get(i, n);
      if (h.first > 0) break;
      st.up(h.second, h.second, INF);
      st.up(h.second + 1, n, -1);
      sum.up(h.second, h.second, 1);
    }
  }
  for (int i = 1; i <= q; i++) cout << resp[i] << endl;
}
