#include <bits/stdc++.h>
template <typename T>
bool chkmax(T &x, T y) {
  return x < y ? x = y, true : false;
}
template <typename T>
bool chkmin(T &x, T y) {
  return x > y ? x = y, true : false;
}
using namespace std;
long long ksm(long long a, long long b) {
  if (!b) return 1;
  long long ns = ksm(a, b >> 1);
  ns = ns * ns % 998244353;
  if (b & 1) ns = ns * a % 998244353;
  return ns;
}
int pl[5500];
struct th {
  int sz;
  int l, r;
  vector<int> pls;
  th *ch[2];
  vector<vector<int> > id;
} p[200005], *rt[70];
int cal(th *a, int l, int r) {
  int p1 = lower_bound(a->pls.begin(), a->pls.end(), l) - a->pls.begin();
  int p2 =
      lower_bound(a->pls.begin(), a->pls.end(), r + 1) - a->pls.begin() - 1;
  if (p1 > p2) return 0;
  return a->id[p1][p2];
}
int cnt = 0;
vector<pair<int, int> > g;
int mer(int x, int y) {
  if (!x) return y;
  if (!y) return x;
  cnt++;
  g.push_back(make_pair(x, y));
  return cnt;
}
int stcnt = 0;
void bdtree(th *a, int l, int r) {
  a->l = l, a->r = r;
  for (int i = l; i <= r; i++) a->pls.push_back(pl[i]);
  int sz = r - l + 1;
  sort(a->pls.begin(), a->pls.end());
  a->id.resize(sz);
  for (int j = 0; j < sz; j++) a->id[j].resize(sz);
  if (sz == 1)
    a->id[0][0] = a->pls[0];
  else {
    int mid = (l + r) >> 1;
    a->ch[0] = &p[stcnt++], a->ch[1] = &p[stcnt++];
    bdtree(a->ch[0], l, mid);
    bdtree(a->ch[1], mid + 1, r);
    for (int i = 0; i < sz; i++)
      for (int j = i; j < sz; j++)
        a->id[i][j] = mer(cal(a->ch[0], a->pls[i], a->pls[j]),
                          cal(a->ch[1], a->pls[i], a->pls[j]));
  }
}
int re[100005];
int main() {
  int n, qs;
  scanf("%d%d", &n, &qs);
  cnt = n;
  for (int i = 1; i <= n; i++) {
    int a;
    scanf("%d", &a), pl[a] = i;
  }
  vector<th *> q;
  int nr = 1;
  while (nr <= n) {
    th *n1 = &p[stcnt++];
    int ur = min(n, nr + 200);
    bdtree(n1, nr, ur);
    q.push_back(n1);
    nr = ur + 1;
  }
  for (int i = 1; i <= qs; i++) {
    int pr = 0;
    int l, r;
    scanf("%d%d", &l, &r);
    for (auto m : q) pr = mer(pr, cal(m, l, r));
    re[i] = pr;
  }
  cout << cnt << endl;
  for (auto h : g) printf("%d %d\n", h.first, h.second);
  for (int i = 1; i <= qs; i++) printf("%d ", re[i]);
  return 0;
}
