#include<iostream>
using namespace std ;
int main(){
    string a,b;
    if(!=(cin>>a>>b)){
        cout<<"Invalid input";
    }
    else if(a.length()!=b.length()){
        cout<<"Invalid input";
    }
    else{
        for(int i =0;i<a.length();i++){
            cout<<a[i]<<b[i]<<endl;
        }
    }
}