#include<iostream>
#include<string>
#include<cctype>
using namespace std;
bool isValid(const string &s)
{
    for(char c:s)
    {
        if(!isalpha(static_cast<unsignedchar>(c)))
        {
            return false;
        }
    }
    return true;
}
int main()
{
    string word1,word2;
    
    cin>> word1;
    cin>> word2;
    
    if(!isValid(word1) || !isValid(word2))
    {
        cout<<"Invalid input";
        return 0;
    }
    string result = "";
    int n1 = word1.length();
    int n2 = word2.length();
    int n= min(n1,n2);
    
    for(int i=0;i<n;i++)
    {
        result += word1[i];
        result += word2[i];
    }
    if(n1>n2)
      result += word1.substr(n);
    else
      result += word2.substr(n);
    cout<<result;
    return 0;
}