蒟蒻在线orz

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=3e5+5;
const ll inf=4e15;
int T;
int n,k;
int a[N];
struct date{
	int x,y;
};
int cnt;
date ans[N];
void div(ll x){
	ll h=x,t=0,mod=1;
	while(x/mod>n) mod*=10;
	while(h){
		while((x*10/mod)%10==0 && x/mod) mod*=10;
		h=x/mod;
		t=x%mod;
		if(!h) break;
		if(t<=a[h] && t>=1){
			cnt++;
			ans[cnt].x=h;
			ans[cnt].y=t;
		}
		mod*=10;
	}
}
bool cmp(date a,date b){
	return a.x==b.x ? a.y<b.y : a.x<b.x;
}
int main(){
	cin>>T;
	while(T--){
		cin>>n>>k;
		for(int i=1;i<=n;i++) cin>>a[i];
		if(k==1){
			printf("0\n");
			continue;
		}
		cnt=0;
		for(ll p=k;p<=inf;p*=k) div(p);
		sort(ans+1,ans+1+cnt,cmp);
		printf("%d\n",cnt);
		for(int i=1;i<=cnt;i++)
			printf("%d %d\n",ans[i].x,ans[i].y);
	}
	return 0;
}
/*
Runtime Error.
Received signal 11: Segmentation fault with invalid memory reference.
*/