#include<bits/stdc++.h>
using namespace std;
using ll=long long;
template<typename T>
ostream& operator << (ostream &out,const vector<T>&x){
	if(x.empty())return out<<"[]";
	out<<'['<<x[0];
	for(int len=x.size(),i=1;i<len;i++)out<<','<<x[i];
	return out<<']';
}
template<typename T>
vector<T> ary(const T *a,int l,int r){
	return vector<T>{a+l,a+1+r};
}
template<typename T>
void debug(T x){
	cerr<<x<<'\n';
}
template<typename T,typename ...S>
void debug(T x,S ...y){
	cerr<<x<<' ',debug(y...);
}
const int N=2e5+10;
int T,n,m,a[N],cnt[N],pre[N],nex[N];
bool chk(int x){
	return pre[x]&&nex[x]<=n&&a[pre[x]]!=a[nex[x]];
}
void del(int x){
	nex[pre[x]]=nex[x],pre[nex[x]]=pre[x];
}
void get(){
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)scanf("%d",&a[i]);
	for(int i=1;i<=n;i++)cnt[a[i]]++;
	for(int i=0;i<=n;i++)nex[i]=i+1,pre[i+1]=i;
	set<int>s;
	for(int i=1;i<=n;i++)if(chk(i))s.insert(i);
	vector<pair<int,int> >ans;
	ans.clear();
	for(int i=1;i<n;i++){
		if(a[i]^a[i+1])ans.push_back({i,i+1});
	}
	for(int t=n-2;t--;){
		if(!s.empty()){
			int i=*s.begin();
			if(cnt[a[i]]==1){
				for(;pre[i]!=1;del(pre[i])){
					ans.push_back({pre[pre[i]],i});
				}
				for(;nex[i]!=n;del(nex[i])){
					ans.push_back({i,nex[nex[i]]});
				}
				if(chk(i)){
					ans.push_back({pre[i],nex[i]});
				}
				break;
			}else{
				s.erase(i);
				if(chk(pre[i]))s.erase(pre[i]);
				if(chk(nex[i]))s.erase(nex[i]);
				ans.push_back({pre[i],nex[i]});
				del(i);
				if(chk(pre[i]))s.insert(pre[i]);
				if(chk(nex[i]))s.insert(nex[i]);
			}
		}else{
			int i=nex[1];
			del(i);
			if(chk(pre[i]))s.insert(pre[i]);
			if(chk(nex[i]))s.insert(nex[i]);
		}
	}
	printf("%lu\n",ans.size());
	for(auto x:ans)printf("%d %d\n",x.first,x.second);
}
void clr(){
	for(int i=1;i<=m;i++)cnt[i]=0;
}
int main(){
	for(scanf("%d",&T);T--;clr())get();
	return 0;
}