#include <bits/stdc++.h>
#pragma GCC optimize("Ofast", "unroll-loops", "omit-frame-pointer", "inline")
#pragma GCC option("arch=native", "tune=native", "no-zero-upper")
#pragma GCC target("avx2")
using namespace std;
template <typename T>
void maxtt(T& t1, T t2) {
  t1 = max(t1, t2);
}
template <typename T>
void mintt(T& t1, T t2) {
  t1 = min(t1, t2);
}
bool debug = 0;
int n, m, k;
int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};
string direc = "RDLU";
const long long MOD2 = (long long)1000000007 * (long long)1000000007;
long long ln, lk, lm;
void etp(bool f = 0) {
  puts(f ? "YES" : "NO");
  exit(0);
}
void addmod(int& x, int y, int mod = 1000000007) {
  x += y;
  if (x >= mod) x -= mod;
  if (x < 0) x += mod;
  assert(x >= 0 && x < mod);
}
void et(int x = -1) {
  printf("%d\n", x);
  exit(0);
}
long long fastPow(long long x, long long y, int mod = 1000000007) {
  long long ans = 1;
  while (y > 0) {
    if (y & 1) ans = (x * ans) % mod;
    x = x * x % mod;
    y >>= 1;
  }
  return ans;
}
long long gcd1(long long x, long long y) { return y ? gcd1(y, x % y) : x; }
const int B = 1 << 8;
int a[(1 << 12) + 5], pos[(1 << 12) + 5], sz;
vector<pair<int, int> > A;
int mg(int u, int v) {
  if (u == 0 || v == 0) return v | u;
  A.push_back({u, v});
  return ++sz;
}
int f[(B * 2) + 2][B + 2][B + 2];
struct mb {
  int L, R;
  int id[(1 << 12) + 5], val[B + 2][B + 2];
  void cal(int rt, int l, int r, vector<int>& vp) {
    if (l == r) {
      assert(vp.size() > 1);
      f[rt][1][1] = pos[vp[1]];
      return;
    }
    int mid = (l + r) / 2;
    vector<int> vl(1), vr(1);
    vector<int> ps(((int)vp.size()) + 2, 0), psr(((int)vp.size()) + 2, 0);
    for (int i = 1; i < vp.size(); i++) {
      if (vp[i] <= mid) {
        vl.push_back(vp[i]);
        ps[i]++;
      } else {
        vr.push_back(vp[i]);
        psr[i]++;
      }
    }
    for (int(i) = 1; (i) <= (int)(vp.size()); (i)++) {
      ps[i] += ps[i - 1];
      psr[i] += psr[i - 1];
    }
    cal((rt << 1), l, mid, vl);
    cal((rt << 1 | 1), mid + 1, r, vr);
    for (int i = 1; i < vp.size(); i++) {
      for (int j = i; j < vp.size(); j++) {
        int A = ps[i - 1] + 1;
        int B = ps[j];
        int C = psr[i - 1] + 1, D = psr[j];
        f[rt][i][j] = mg(f[(rt << 1)][A][B], f[(rt << 1 | 1)][C][D]);
      }
    }
  }
  void build() {
    vector<int> vp(1);
    for (int(i) = 1; (i) <= (int)(n); (i)++) {
      id[i] = id[i - 1];
      if (L <= a[i] && a[i] <= R) {
        id[i]++;
        vp.push_back(a[i]);
      }
    }
    cal(1, L, R, vp);
    for (int i = 1; i < vp.size(); i++) {
      for (int j = i; j < vp.size(); j++) {
        val[i][j] = f[1][i][j];
      }
    }
  }
  int qy(int l, int r) { return val[id[l - 1] + 1][id[r]]; }
} blk[17];
void fmain(int tid) {
  scanf("%d%d", &n, &m);
  for (int(i) = 1; (i) <= (int)(n); (i)++) {
    scanf("%d", a + i);
    pos[a[i]] = i;
  }
  sz = n;
  for (int i = 1; (i - 1) * B + 1 <= n; i++) {
    blk[i].L = (i - 1) * B + 1;
    blk[i].R = min(n, i * B);
    blk[i].build();
  }
  vector<int> ans(m + 2, 0);
  for (int(i) = 1; (i) <= (int)(m); (i)++) {
    int l, r;
    scanf("%d%d", &l, &r);
    for (int j = 1; (j - 1) * B + 1 <= n; j++) {
      ans[i] = mg(ans[i], blk[j].qy(l, r));
    }
  }
  printf("%d\n", sz);
  for (auto p : A) printf("%d %d\n", p.first, p.second);
  for (int(i) = 1; (i) <= (int)(m); (i)++) printf("%d ", ans[i]);
  puts("");
}
int main() {
  int t = 1;
  for (int(i) = 1; (i) <= (int)(t); (i)++) {
    fmain(i);
  }
  return 0;
}
