#include<iostream>
#include<cctype>
using namespace std;
int main()
{
    string n1,n2;
    getline(cin,n1);
    getline(cin,n2);
   for(int i=0;i<n1.length();i++)
   {
       if(!isalpha(n1[i]))
       {
           cout<<"Invalid input";
           return 0;
           
       }
   }
      for(int i=0;i<n2.length();i++)
   {
       if(!isalpha(n2[i]))
       {
           cout<<"Invalid input";
           return 0;
           
       }
   }
   string result;
   int i=0;
   while(i<n1.length() && i<n2.length())
   {
       result+=n1[i];
       result+=n1[i];
       i++
   }
   while(i<n1.length())
   {
       result+=n1[i++];
   }
     while(i<n2.length())
   {
       result+=n2[i++];
   }
   cout<<result;
}