H

#include<bits/stdc++.h>
#include<iostream>
#include<cmath>
#include<iomanip>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<vector>
#include<utility>
using namespace std;

#define ll long long
#define nl '\n'
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define rall(s)  s.rbegin(), s.rend()
#define getline(s) getline(cin>>ws,s)
#define ceill(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
#define pi  3.141592653589793

/*
███╗░░██╗███████╗░██████╗░███╗░░░███╗
████╗░██║██╔════╝██╔════╝░████╗░████║
██╔██╗██║█████╗░░██║░░██╗░██╔████╔██║
██║╚████║██╔══╝░░██║░░╚██╗██║╚██╔╝██║
██║░╚███║███████╗╚██████╔╝██║░╚═╝░██║
╚═╝░░╚══╝╚══════╝░╚═════╝░╚═╝░░░░░╚═╝

*/

void Fast_IO(){
ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
// freopen("filename.in", "r", stdin);
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
#endif
}




void solve(){
ll n,s; cin>>n>>s;
vector<ll>v(n);
ll start =9;
if((s>n*9) or (s%2== 1 and n%2 ==0)) return void (cout<<-1<<nl);
int l=0,r=n-1, mid = n/2;
while(s>0){
    if(s - 2*start< 0) start--;
    else{
        s -= 2*start;
        v[l++] = start;
        v[r--] = start;
    }
    if(l>=r) break;
}


if(s>=0 and s <=9 and n%2){
     v[mid] = s;
     s=0;
}

if(v[0] == 0) return void(cout<<-1<<nl);
if(s == 0){
    for(auto i:v) cout<<i;
    cout<<nl;
    return;
}else return void (cout<<-1<<nl);




}

int main(){
    Fast_IO();
int t =1;
cin>>t;
while(t--){
solve();
}
return 0;
}