#include <bits/stdc++.h>
using namespace std;
inline int read() {
  char ch = getchar();
  int nega = 1;
  while (!isdigit(ch)) {
    if (ch == '-') nega = -1;
    ch = getchar();
  }
  int ans = 0;
  while (isdigit(ch)) {
    ans = ans * 10 + ch - 48;
    ch = getchar();
  }
  if (nega == -1) return -ans;
  return ans;
}
int b[5005];
int n, q;
struct Node {
  vector<int> v;
  map<pair<int, int>, int> m;
};
Node a[5005 * 4];
vector<pair<int, int> > c;
int ans[5005 * 20];
void build(int u, int l, int r) {
  if (l == r) {
    a[u].v.push_back(b[l]);
    return;
  }
  int mid = (l + r) / 2;
  build((u << 1), l, mid);
  build((u << 1 | 1), mid + 1, r);
  int i = 0, j = 0;
  while (i < (int)a[(u << 1)].v.size() && j < (int)a[(u << 1 | 1)].v.size()) {
    if (a[(u << 1)].v[i] < a[(u << 1 | 1)].v[j])
      a[u].v.push_back(a[(u << 1)].v[i++]);
    else
      a[u].v.push_back(a[(u << 1 | 1)].v[j++]);
  }
  while (i < (int)a[(u << 1)].v.size()) a[u].v.push_back(a[(u << 1)].v[i++]);
  while (j < (int)a[(u << 1 | 1)].v.size())
    a[u].v.push_back(a[(u << 1 | 1)].v[j++]);
}
int solve(int u, int L, int R) {
  int l = lower_bound(a[u].v.begin(), a[u].v.end(), L) - a[u].v.begin();
  int r = upper_bound(a[u].v.begin(), a[u].v.end(), R) - a[u].v.begin();
  if (l == (int)a[u].v.size() || l == r) return -1;
  if (l + 1 == r) return a[u].v[l];
  if (a[u].m[make_pair(l, r)]) return a[u].m[make_pair(l, r)];
  int x = solve((u << 1), L, R), y = solve((u << 1 | 1), L, R);
  if (x != -1 && y != -1) {
    c.emplace_back(x, y);
    return a[u].m[make_pair(l, r)] = c.size() + n;
  } else
    return a[u].m[make_pair(l, r)] = max(x, y);
}
signed main() {
  cin >> n >> q;
  for (int i = 1; i <= n; i++) b[read()] = i;
  build(1, 1, n);
  for (int i = 1; i <= q; i++) {
    int l = read(), r = read();
    ans[i] = solve(1, l, r);
  }
  cout << c.size() + n << endl;
  for (auto [x, y] : c) printf("%d %d\n", x, y);
  for (int i = 1; i <= q; i++) printf("%d ", ans[i]);
  return 0;
}
