#include<bits/stdc++.h>
#define int long long
#define fr(i,a,b) for(int i(a),end##i(b);i<=end##i;i++)
#define fd(i,a,b) for(int i(a),end##i(b);i>=end##i;i--)
#define mk make_pair
#define pii pair<int,int>
#define fi first
#define se second
#define pb push_back
using namespace std;
int t,x,k;
int p[100],ans[100];
void out(){
	int flag=0;
	fd(i,50,1){
		flag|=(ans[i]!=0);
		if(flag)cout<<ans[i];	
	}
	cout<<'\n';
}
signed main(){
#ifdef pig
	freopen("pig.in","r",stdin);
	freopen("pig.out","w",stdout);
#endif
	cin>>t;
	while(t--){
		scanf("%lld%lld",&x,&k);
		/*if(n<k){
		  cout<<-1<<'\n';
		  continue;
		  }*/
		fr(i,1,50){
			p[i]=x%10;
			x/=10;
		}
		fr(i,1,50)ans[i]=0;
		int pos=0;
		/*fr(i,k+1,19)if(p[i]!=9){
			pos=i-1;break;
		}
		fr(i,1,k)ans+=T[pos-i]*(9-p[pos-i+1]);
		ans+=T[pos-k];*/
		fr(i,1,20)if(p[i]&&p[i+k]!=9){
			fr(j,i,i+k-1)ans[j]+=9-p[j];
			ans[i]++;
			out();
			goto End;
		}
		cout<<-1<<'\n';
		End:;
	}
	return 0;
}