#include<iostream>
#include<string>
using namespace std;
bool isValid(string s){
    for(char c:s)
    {
        if(!isalpha(c))
        return false;
    }
    return true;
}
int main()
{
    string word1,word2;
    getline(cin,word1)
    getline(cin.word2);
    if(!isValid(word1)||!isValid(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++
    }
    result+= word1.substr(i);
    result+= word2.substr(i);
    cout<<result;
    return 0;
}