#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 n1 = word1.length();
    int n2 = word2.length();
    int i = 0;
    
    while (i < n1 && I < n2) {
        result += word[i];
        result += word2[i];
        i++;
    }
    
    while (i < n1) {
        result += word1[i];
        i++;
    }
    
    while (i < n2) {
        result += word2[i];
        i++;
    }
    cout<< result;
    return 0;
}