#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using i128 = __int128;
using u128 = unsigned __int128;
template <typename T>
void chkmax(T &x, const T &y) {
  if (x < y) x = y;
}
template <typename T>
void chkmin(T &x, const T &y) {
  if (y < x) x = y;
}
constexpr int MAXN = 2e5 + 10;
int n, m, a[MAXN], pre[MAXN], nxt[MAXN], qu[MAXN], hd, tl, cnt[MAXN], tp;
bool vis[MAXN];
pair<int, int> ans[MAXN * 2];
bool check(int u) { return a[pre[u]] != a[nxt[u]]; }
void push(int u) {
  if (vis[u]) return;
  if (check(u)) {
    vis[u] = true;
    qu[tl++] = u;
    if (tl == MAXN) tl = 0;
  }
}
bool erase(int u) {
  if (cnt[a[u]] == 1) {
    for (int i = nxt[u]; i != n; i = nxt[i]) ans[++tp] = {u, nxt[i]};
    for (int i = pre[u]; i != 1; i = pre[i]) ans[++tp] = {pre[i], u};
    if (a[1] != a[n]) ans[++tp] = {1, n};
    return true;
  }
  --cnt[a[u]];
  if (a[pre[u]] != a[nxt[u]]) ans[++tp] = {pre[u], nxt[u]};
  nxt[pre[u]] = nxt[u];
  pre[nxt[u]] = pre[u];
  push(pre[u]);
  push(nxt[u]);
  return false;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int cas;
  cin >> cas;
  while (cas--) {
    cin >> n >> m;
    for (int i = 1; i <= n; ++i) cin >> a[i];
    fill(cnt + 1, cnt + m + 1, 0);
    for (int i = 1; i <= n; ++i) {
      ++cnt[a[i]];
      pre[i] = i - 1;
      nxt[i] = i + 1;
    }
    fill(vis + 1, vis + n + 1, false);
    vis[1] = vis[n] = true;
    hd = tl = tp = 0;
    for (int i = 1; i <= n; ++i) push(i);
    for (int i = 1; i < n; ++i)
      if (a[i] != a[i + 1]) ans[++tp] = {i, i + 1};
    for (int turn = 1; turn <= n - 2; ++turn) {
      while (hd != tl && !check(qu[hd])) {
        vis[qu[hd++]] = false;
        if (hd == MAXN) hd = 0;
      }
      if (hd == tl) {
        if (erase(nxt[1])) break;
      } else {
        if (erase(qu[hd++])) break;
        if (hd == MAXN) hd = 0;
      }
    }
    cout << tp << "\n";
    for (int i = 1; i <= tp; ++i)
      cout << ans[i].first << " " << ans[i].second << "\n";
  }
  return 0;
}
/*
g++ F.cpp -o F -std=c++14 -O2 -Wall -Wextra -Wshadow -g
-fsanitize=address,undefined
*/