//Stephen Siena
//CSE 40872 - Problem 8
//September 18, 2009

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

void findCommonString(string str1, string str2);

int main(){

  string word1;
  string word2;

  while(true){
    cin >> word1;
    if (cin.eof()) break;
    cin >> word2;

    findCommonString(word1, word2);
  }

  return 0;
}

void findCommonString(string str1, string str2){

  sort(str1.begin(), str1.end());
  sort(str2.begin(), str2.end());

  string commonPerm;

  string::iterator it1 = str1.begin();
  string::iterator it2 = str2.begin();

  while(it1 != str1.end() && it2 != str2.end()){
    if (*it1 > *it2)
      it2++;
    else if (*it1 < *it2)
      it1++;
    else{
      commonPerm += *it1;
      it1++;
      it2++;
    }
  }

  cout << commonPerm << endl;

}