//A tree without skin will surely die.
//A man without face will be alive.
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define mid ((l+r)>>1)
#define lowbit(x) (x&-x)
#define all(x) (x).begin(),(x).end()
#define rep(i,j,k) for (int i=j;i<=k;++i)
#define per(i,j,k) for (int i=j;i>=k;--i)
int const N=2e5+10;
int n,m,a[N],cnt[N];
set<int>all,dif;
vector< pair<int,int> >ans;
inline void push(int id){
	if (id==1 || id==n) return;
	auto it=all.find(id);
	auto pr=it,nt=it;
	--pr,++nt;
	if (a[*pr]!=a[*nt]) dif.insert(id);
}
inline void del(int k){
	auto it=all.find(k);
	auto pr=it,nt=it;
	--pr,++nt;
	int P=*pr,N=*nt;
	if (a[P]!=a[N]) ans.push_back({P,N});
	if (dif.count(*pr)) dif.erase(P);
	if (dif.count(*nt)) dif.erase(N);
	dif.erase(k),all.erase(k),--cnt[a[k]];
	push(P),push(N);
}
inline void solve(){
	cin>>n>>m,all.clear(),dif.clear(),ans.clear();
	rep(i,1,m) cnt[i]=0;
	rep(i,1,n) cin>>a[i],++cnt[a[i]];
	rep(i,1,n) all.insert(i);
	rep(i,2,n-1)
		if (a[i-1]!=a[i+1]) dif.insert(i);
	rep(i,1,n-1)
		if (a[i]!=a[i+1]) ans.push_back({i,i+1});
	rep(i,1,n-2){
		if (!dif.size()){
			del(*(++all.begin()));
			continue;
		}
		int g=*dif.begin();
		if (cnt[a[g]]==1){
			vector<int>q;
			for (auto i:all)
				if (i!=1 && i!=n && i!=g) q.push_back(i);
			for (auto i:q) del(i);
			del(g);
			break;
		}
		del(g);
	}
	cout<<ans.size()<<'\n';
	for (auto i:ans) cout<<i.first<<' '<<i.second<<'\n';
}
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	int t=1;
	cin>>t;
	while (t--) solve();
	cerr<<"Time: "<<(double)clock()/CLOCKS_PER_SEC<<" s\n";
	return 0;
}