#include<iostream>
#include<vector>
#include<string>
#include<map>
#include<queue>
#include<set>
#include<deque>
#include<cmath>
#include<algorithm>
#include<functional>
#include<stack>
#include<tuple>
#include<bitset>
using namespace std;

int main() {
	string s, t;
	cin >> s >> t;
	int n;
	cin >> n;

	cout << s;
	for (int i = 0; i < n; i++)cout << '_' << t;
	cout << endl;
}