#include<iostream>
#include<string>
using namespace std;
bool invalid (string s){
    if(s.length()<1 || s.length()>100)
       return false;
    for (char ch : s){
        if(!isalpha(ch))
           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 i =0;
    while (i<word1.length()&&i<word2.length()){
        result+=word1[i];
        result+=word2[i];
        i++;
    }
    while (i<word1.length()){
        result+=word1[i++];
        
    }
    while (i<word2.length()){
        result+=word2[i++];
    }
    cout<<result;
    return 0;
}