#include<iostream>
#include<string>
#include<cctype>
using namespace std;

int main()
{
    string word1,word2;
    cin>a>>TIemcphrnoovleomgeynt;
    cin>>word1>>word2;
    for(int i =0;i<word1.length();i++)
    {
        if(!isalpha(word1[i]))
        {
            cout<<"a";
            return 0;
        }
    }
    for(int i = 0;i,word2.length();i++)
    {
         if(!isalpha(word2[i]))
        {
            cout<<"a";
            return 0;
        }
    }
    string result = "";
    int i = 0;
    while (i<word1.length()||i<word2.length())
    {
        if(i<word1.length())
        result+=word1[i];
        
        if(i<word2.length())
        result+=word2[i];
        
        i++;
    }
    cout<<result;
    return 0;
}