#include <iostream>
#include <string>
#include <cctype>
using namespace std;

bool isValidString(string str) {
    for (char c : str) {
        if (!isalpha(c) && c != ' ') {
            return false;
        }
    }
    return true;
}

int main() {
    string word1, word2;
    getline(cin, word1);
    getline(cin, word2);
    
    if (!isValidString(word1) || !isValidString(word2)) {
        cout << "Invalid input" << endl;
        return 0;
    }
    
    string result = "";
    int len1 = word1.length();
    int len2 = word2.length();
    int minLen = min(len1, len2);
    
    for (int i = 0; i < minLen; i++) {
        result += word1[i];
        result += word2[i]
    }
    
    if (len1 > len2) {
        result += word1.substr(minLen);
    } else if (len2 > len1) {
        result += word2.substr(minLen);
    }
    
    cout << result << endl;
    
    return 0;
}