// editor5
#include<iostream>
#include<cctype>
using namespace std;
bool isValid(string s)
{
    for(char c:s)
    {
        if(!isalpha(c))return false;
    }
    return true;
}
int amin()
{
    string word1, word2;
    cin >> word1 >>word2;
    if(!isValid(word1)||!isValid(word2)){
        cout<<"Invalid input";
        return 0;
    }
    while (i < word1.length() || j < word2.length()){
        if(i < word1.length())result +=word1[i++];
        if(j <word2.length()) result +=word2[j++];
    }
    cout<<result;
    return 0;
}