#include<iostream>
#include<string>
#include<cctype>
using namespace std;
bool isValid(const string& s){
    for(char c : s){
        if(!isspace(c)){
         return false;
        }
    }
    return true;
}
int main(){
    if(!(getline(cin, word1) && getline(cin, word2))) return 0;
    if(!isValid(word1) || !osVaild(word2)){
        cout<<"Invalid input"<<endl;
        return 0;
    }
    string merged ="";
    int i=0,j=0;
    int n1 = word1.length();
    int n2 = word2.length();
    while(i<n1 && j<n2){
        merged += word1[i++];
    }
    while(i<n1){
        merged += word2[j++];
    }
    cout<<merged<<endl;
    return 0;
}