#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int N=3*1e5+10;
struct node {
	int mo,d;
}b[10*N];
bool cmp(node x,node y){
	if (x.mo!=y.mo) return x.mo<y.mo;
		else return x.d<y.d;
}
ll n,k,t,mon[N];
signed main(){
	std::ios::sync_with_stdio(0);
	std::cin.tie(0);std::cout.tie(0);
	cin>>t;
	for (int i=1;i<=t;i++){
		ll ans=0;
		cin>>n>>k;
//		cout<<k<<endl;
		ll o=0;
		for (int j=1;j<=n;j++){
			cin>>mon[j];
			o=max(o,mon[j]);
		}
		 if (k==1){
			cout<<"0"<<endl;
			continue;
		}
		ll u=o;
		ll x=0;
		while (u){
			u/=10;
			x++;
		}
		ll m=n*pow(10,x)+o;
//		ll m=n;
		ll y=1;
		for (int j=1;y<=m;j++){
			y*=k;
			ll uuu=y;
			ll s=0;
			while (uuu){
				uuu/=10;
				s++;
			}
			for (int l=1;l<s;l++){
//				int ou=ceil(log10(y));
				ll month=y/pow(10,s-l);
				ll day=y%int(pow(10,s-l));
				int uo=ceil(log10(day+1));
				int yo=month*pow(10,uo)+day;
//				cout<<month<<' '<<day<<' '<<yo<<endl;
				if (month<=n&&mon[month]>=day&&yo==y){
					b[++ans].mo=month;
					b[ans].d=day;
				} 
			}
		}
		sort(b+1,b+1+ans,cmp);
		cout<<ans<<endl;
		for (int j=1;j<=ans;j++){
			cout<<b[j].mo<<' '<<b[j].d<<endl; 
		}
	}
    return 0;
}
/*
20 5
1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000
*/