#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define fi first
#define se second
int main(){
    string s, t;
    int n;
    cin >> s >> t >> n;
    for(int i = 0; i < n; i++){
        s.push_back('_');
        s += t;
    }
    cout << s << endl;
    return 0;
}