// editor5
#include<iostream>
#include<algorithm>
#include<string>
using namespace std;
bool valid(string str)
{
  for(char ch : str)
  {
      if(!isalpha(ch))
      {
         return false; 
      }
    }
    return true;
}
int main()
{
    string word1;
    string word2;
    cin>>word1;
    cin>>word2;
    
    if(!valid(word1) || !valid(word2))
    {
        cout<<"Invalid input";
        return 0;
    }
    string result =" ";
    int i=0;
    
    while(i<word1.length() && i<word2.length())
    {
        result+=word1[i];
        result+=word2[i];
        i++;
    }
    while(i<word1.length())
    {
        result+=word1[i];
        i++;
    }
    while(i<word2.length())
    {
        result+=word2[i];
        i++;
    }
    cout<<result;
    r
}