// editor5
#include<iostream>
#include<string>
using namespace std;
bool check(string s)
{
    for(char i:s)
    {
        if(!isalpha(1))
        return true;
    }
    return false;
}
int main()
{
    string w1,w2;
    cin >> w1;
    cin >> w2;
    if(!(w1.size()>=1 && w1.size()<=100 && w2.size()>=1 && w2.size()<=100))
    return 0;
    if(check(w1) || check(w2))
    {
        cout<<"Invalid input";
        return 0;
    }
    string ss,subs;
    if(w1.size()>w2.size())
    {
        ss =w2;
        subs =w1.substr; (w2.size());
        w1 = w2.substr(0, w2.size());
    }
    else if(w1.size()<w2.size())
    {
        ss =w1;
        subs = w2.substr(w1.size());
        w2 = w2.substr(0, w1.size());
    }
    else
    {
        ss = w2;
        subs ="";
    }
    string rs ="";
    for(int i=0;i<<ss.size();i++)
    {
        rs += w1.at(i);
        rs += w2.at(i);
    }
    rs += subs;
    cout << rs;
    return 0;
}