#include <bits/stdc++.h>
using namespace std;
string s1,a1,s2,a2;

int main(){

cin>>a1;
for (int i = 1; i < a1.size(); i++) {
  if (a1[i] % 2 == a1[i-1] % 2) {
    s1 += max(a1[i], a1[i-1]);
  }
}



cin>>a2;
for (int i = 1; i < a2.size(); i++) {
  if (a2[i] % 2 == a2[i-1] % 2) {
    s2 += max(a2[i], a2[i-1]);
  }
}

if(s1==s2)cout<<s1<<endl;
    else cout<<s1<<endl<<s2<<endl;


    return 0;
}