#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
bool memBeg;
template<typename T,typename TT> void chkmin(T &x,TT y) {if(x>y) x=y;}
template<typename T,typename TT> void chkmax(T &x,TT y) {if(x<y) x=y;}
constexpr int mod=998244353;
void inc(int &x,int y) {x+=y; x-=(x>=mod)*mod;}
void dec(int &x,int y) {x-=y; x+=(x<0)*mod;}
constexpr int add(int x,int y) {return (x+y>=mod)?x+y-mod:x+y;}
constexpr int sub(int x,int y) {return (x<y)?x-y+mod:x-y;}
constexpr int quick_pow(int x,ll times,int ret=1) {
    for(;times;times>>=1,x=1ll*x*x%mod) if(times&1) ret=1ll*ret*x%mod;
    return ret;
}
constexpr int maxn=2e5+5;
constexpr int maxm=2e5+5;
int n,m,a[maxn],ppre[maxn],pnxt[maxn],occ[maxm];
queue<int> cand;
bool alive[maxn];
vector<pair<int,int>> plan;
void mian() {
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++) scanf("%d",&a[i]);
    memset(occ,0,sizeof(int)*(m+1));
    iota(ppre+1,ppre+n+2,0);
    iota(pnxt,pnxt+n+1,1);
    for(int i=1;i<=n;i++) occ[a[i]]++;
    while(!cand.empty()) cand.pop();
    int ret=0;
    plan.clear();
    for(int i=1;i<n;i++) if(a[i]!=a[i+1]) {
        ret++; plan.emplace_back(i,i+1);
    }
    for(int i=2;i<n;i++) if(a[i-1]!=a[i+1]) cand.emplace(i);
    fill(alive,alive+n+1,true);
    int rst=n;
    while(rst>2) {
        while(!cand.empty()) {
            int cur=cand.front();
            // printf("cur = %d, alive = %d, ppre = %d, pnxt = %d\n",cur,alive[cur],ppre[cur],pnxt[cur]);
            cand.pop();
            if(!alive[cur]||a[ppre[cur]]==a[pnxt[cur]]) continue;
            // printf("cur = %d\n",cur);
            if(occ[a[cur]]==1) {
                ret+=rst-3+(a[1]!=a[n]);
                for(int i=pnxt[cur];i!=n;i=pnxt[i]) {
                    plan.emplace_back(cur,pnxt[i]);
                }
                for(int i=ppre[cur];i!=1;i=ppre[i]) {
                    plan.emplace_back(ppre[i],cur);
                }
                if(a[1]!=a[n]) plan.emplace_back(1,n);
                rst=0; break;
            }
            alive[cur]=false; ret++; rst--; occ[a[cur]]--;
            plan.emplace_back(ppre[cur],pnxt[cur]);
            pnxt[ppre[cur]]=pnxt[cur];
            ppre[pnxt[cur]]=ppre[cur];
            // printf("cur = %d, pnxt = %d, ppre = %d\n",cur,pnxt[cur],ppre[cur]);
            if(pnxt[cur]!=n&&a[ppre[cur]]!=a[pnxt[pnxt[cur]]]) cand.emplace(pnxt[cur]);
            if(ppre[cur]!=1&&a[ppre[ppre[cur]]]!=a[pnxt[cur]]) cand.emplace(ppre[cur]);
        }
        if(--rst<=2) break;
        alive[pnxt[1]]=false; occ[a[pnxt[1]]]--;
        ppre[pnxt[pnxt[1]]]=1;
        pnxt[1]=pnxt[pnxt[1]];
        // printf("pnxt[pnxt[1] = %d] = %d\n",pnxt[1],pnxt[pnxt[1]]);
        if(a[1]!=a[pnxt[pnxt[1]]]) cand.emplace(pnxt[1]);
    }
    printf("%d\n",ret);
    for(auto v:plan) printf("%d %d\n",v.first,v.second);
}
bool memEn;
void fl() {
    freopen(".in","r",stdin);
    freopen(".out","w",stdout);
}
int main() {
    fprintf(stderr,"%.24lf\n",fabs(&memEn-&memBeg)/1024.0/1024.0);
    // fl();
    int _; scanf("%d",&_);
    while(_--) mian();
    return 0;
}