#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: houshanglin
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2076 kb
****************************************************************/