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