#include <iostream>
#include <string>
#include <cctype>
#include <algorithm>
using namespace std;
int main (){
    string w1,w2;
    getline(cin,w1);
    getline(cin,w2);
    for(char c:w1+w2)
    if(!isalpha(c)){
        cout<< "Invalid input";
        return 0;
    }
    string result = " ";
    int n=max(w1. length(), w2.length());
    for(int i=0;i<n;i++){
        if(i<w1. length())result+=w1[i];
        if(i<w2. length()result +=w2[i];
    }
    cout<<result;
    return 0;
}