SKMP

#include<bits/stdc++.h>
using namespace std;
#define suni ios_base::sync_with_stdio(false);cin.tie(0); cout.tie(0)
#define ll long long
#define pb push_back
#define tt int t;cin>>t;while(t--)
#define endl "\n"
int main()
{
    suni;
    tt
    {
        string s,p;
        cin>>s>>p;
        int freqs[26], freqp[26];
        memset(freqs,0,sizeof(freqs));
        memset(freqp,0,sizeof(freqp));
        for(int i=0;i<s.length();i++) freqs[s[i]-97]+=1;
        for(int i=0;i<p.length();i++) freqp[p[i]-97]+=1;
        for(int i=0;i<26;i++) freqs[i]=freqs[i]-freqp[i];
        bool flag=0,flag1=0;
        string str="";
        for(int i=0;i<26;i++){
            for(int j=0;j<freqs[i];j++){
                char ch=i+97;
                str+=ch;
            }
        }
        //cout<<str<<endl;
        string ans,ans1;
        int j,k;
        for(int i=0;i<str.length();i++){
            if(p[0]==str[i] && flag==0){
                ans1+=str.substr(0,i)+p;
                flag=0;
                k=i;
            }
            else if(p[0]<str[i] && flag1==0){
                ans+=str.substr(0,i)+p;
                flag1=1;
                j=i;
            }
        }
        string final;
        if(flag1==1 && flag==1){
            if(ans<ans1)
              final= ans+str.substr(j,str.length()-j);
            else
              final=ans1+str.substr(k,str.length()-k);
        }
        else if(flag1==1)
           final= ans+str.substr(j,str.length()-j);
        else if(flag==1)
            final=ans1+str.substr(k,str.length()-k);
        else
           final=str+p;
           cout<<final<<endl;
    }
    return 0;
}