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