#include<bits/stdc++.h>
using namespace std;
int main(){
    int i,p,q;
    string a,b;
    cin>>b>>a;
    cin>>q;
    for(i=0;i<q;i++){
        cout<<a[i];
    }
    for(i=0;i<b.size();i++){
        cout<<b[i];
    }
    for(i=q;i<a.size();i++){
        cout<<a[i];
    }
    return 0;
}
/**************************************************************
	Problem: 2020
	User: jiangyuanfeng
	Language: C++
	Result: Accepted
	Time:24 ms
	Memory:2076 kb
****************************************************************/