#include "bits/stdc++.h"
#define int long long
#define all(x) x.begin(), x.end()
template<typename... Args>
void debug(Args... args) {
    ((std::cout << args << " "), ...);
    std::cout << "\n";
}
void solve(){
    std::string s, t;
    int n;
    std::cin >> s >> t >> n;
    std::cout << s;
    while(n --) std::cout << "_" << t;
}

signed main(){
    std::ios::sync_with_stdio(false); std::cin.tie(0);
    solve();
    return 0;
}