DSA03016 - SỐ NHỎ NHẤT

//Made By Phuong Nam PROPTIT <3//
#pragma GCC Optimize("O3")
#include<bits/stdc++.h>
#include<string>
#include<vector>
#define alphaa "abcdefghijklmnopqrstuvwxyz"
#define ALPHAA "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
#define f(i,a,b) for(int i=a;i<=b;i++)
#define f1(i,n) for(int i=1;i<=n;i++)
#define f0(i,n) for(int i=0;i<n;i++)
#define ff(i,b,a) for(int i=b;i>=a;i--)
#define el cout<<'\n'
#define fi first
#define se second
#define eb emplace_back
#define pk pop_back
#define vi vector<int>
#define vl vector<ll>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define all(s) s.begin(),s.end()
using namespace std;
typedef long long ll;
const int N=1e6+3;
const int MOD=1e9+7;
template<class X,class Y>
    void minimize(X &x,const Y &y) {
        if (x>y) x=y;
    }
template<class X,class Y>
    void maximize(X &x,const Y &y) {
        if (x<y) x=y;
    }
template<class T>
    T Abs(const T &x) {
        return (x<0?-x:x);
    }
void xuly()
{
   int s,d;
   cin>>s>>d;
   vi v;
   if(s==d)
   {
       f1(i,d) cout<<1;
       el;
       return;
   }
   if(9*d<s) return cout<<-1<<'\n',void();
   while(s>0)
   {
       d--;
       if(s>=9)
       {
           v.eb(9);
           s-=9;
       }
       else
       {
           v.eb(s);
           break;
       }
   }
   if(d==0)
   {
       ff(i,v.size()-1,0) cout<<v[i];
       el;
       return;
   }
   if(d<0) return cout<<-1<<'\n',void();
   v[v.size()-1]--;
   while(d>=2)
   {
     v.eb(0);
    d--;
   }
   v.eb(1);
   ff(i,v.size()-1,0) cout<<v[i];
   el;
}
int main()
{
  ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
  int t=1;
  cin>>t;
  while(t--) xuly();
  return 0;
}
//-----YEU CODE HON CRUSH-----//